This is par for the course in the "study" material that they will cover with potential recruits. This happens very early in the indoctrination process. The goal is to create a fear and dread of the devil, and to be suspicious of anyone who may be trying to stop you from learning what the JWs are trying to teach (aka, The Truth™).
Here is an excerpt from the second chapter of the study book You Can Live Forever In Paradise On Earth (1989 edition):
Chapter
2An
EnemyofEverlastingLifeHAPPINESS on earth—nearly everyone wants it. Then why are so many unhappy? What is wrong? Since almost everybody wants peace, why do nations go to war and why do people hate one another? Is there some guiding force that moves them to do these bad things? Could it be that a common invisible power controls the nations?
2
Many have wondered about this when they have considered the terrible cruelty of mankind—the fearful gases used in warfare to choke and burn persons to death, as well as the napalm bombs and the atomic bombs. Also, consider the flamethrower, the concentration camps, the mass murder of millions of helpless people, such as in Cambodia in recent years. Do you think that all these evils simply happened by chance? While man is capable on his own of committing terrible deeds, when you consider the gross wickedness of his acts, does it not seem that he has been influenced by an evil, invisible power?3
There is no need to guess at the matter. The Bible clearly shows that an intelligent unseen person has been controlling both men and nations. In the Bible, Jesus Christ calls this powerful one "the ruler of this world." (John 12:31; 14:30; 16:11) Who is he? 4
To help us to find out who he is, think about what happened at the beginning of Jesus’ ministry here on earth. The Bible tells us that after Jesus was baptized he went into the wilderness where he was tempted by an unseen creature called Satan the Devil. Part of that tempting is described this way: "Again the Devil took him along to an unusually high mountain, and showed him all the kingdoms of the world and their glory, and he said to him: ‘All these things I will give you if you fall down and do an act of worship to me.’"—Matthew 4:8, 9.5
Think about what the Devil offered Jesus Christ. It was "allthekingdomsoftheworld." Did all these worldly governments really belong to the Devil? Yes, for how else could he have offered them to Jesus? Jesus did not deny that they were Satan’s, which he would have done if Satan did not own them. Satan is really the unseen ruler of all the nations of the world! The Bible plainly says: "The whole world is lying in the power of the wicked one." (1 John 5:19) God’s Word, in fact, calls Satan "the god of this system of things."—2 Corinthians 4:4. 6
This information helps us to understand why Jesus said: "My kingdom is no part of this world." (John 18:36) It also helps us to understand why nations hate and try to destroy one another when it is the desire of all normal persons to live at peace. Yes, "Satan . . . is misleading the entire inhabited earth." (Revelation 12:9) He would like to mislead us too. He does not want us to receive God’s gift of everlasting life. So we have to fight to keep from being influenced by him to do what is bad. (Ephesians 6:12) We need to know about Satan and how he works in order to resist his efforts to mislead us.
WHO
THEDEVILIS 7
Satan the Devil is a real person. He is not merely the evil in all mankind, as some persons may believe. Of course, humans cannot see the Devil, for the same reason that they cannot see God. Both God and the Devil are spirit persons, forms of life higher than humans and unseen to our eyes.—John 4:24. 8
‘But if God is love,’ someone may ask, ‘why did he make the Devil?’ (1 John 4:8) The fact is, God did not create the Devil. ‘Yet if God created everyone,’ a person may say, ‘he must have created the Devil. Who else could have? Where did the Devil come from?’9
The Bible explains that God created many, many spirit persons similar to himself. In the Bible, these spirits are called angels. Also, they are called "sons of God." (Job 38:7; Psalm 104:4; Hebrews 1:7, 13, 14) God created them all perfect. Not one of them was a devil, or a satan. The word "devil" means slanderer and the word "satan" means opposer. 10
The time came, however, when one of these spirit sons of God made himself the Devil, that is, a hateful liar who speaks bad things about another. He also made himself Satan, that is, an opposer of God. He was not created that way, but later became that kind of person. To illustrate: A thief is not born a thief. He may have come from a good family, having honest parents and law-abiding brothers and sisters. But his own desire for what money can buy is what may have caused him to become a thief. How, then, did one of God’s spirit sons make himself Satan the Devil?11
The angel that became the Devil was present when God created the earth and later the first human couple, Adam and Eve. (Job 38:4, 7) So he would have heard God tell them to have children. (Genesis 1:27, 28) He knew that after a while the whole earth would be filled with righteous people worshiping God. That was God’s purpose. However, this angel thought a great deal of his own beauty and intelligence and wanted to receive for himself the worship that would be given to God. (Ezekiel 28:13-15; Matthew 4:10) Instead of putting this wrong desire out of his mind, he kept thinking about it. This led to his taking action to obtain the honor and importance he desired. What did he do?—James 1:14, 15. 12
The rebellious angel used a lowly serpent to speak to the first woman, Eve. He did this much as a skilled person can make it seem as if a nearby animal or a dummy figure is talking. But it was really this rebellious angel, the one called in the Bible "the original serpent," who was speaking to Eve. (Revelation 12:9) He said that God was not telling her the truth, and was holding back from her knowledge that she should have. (Genesis 3:1-5) This was a hateful lie and it made him a devil. He thus became also an opposer of God, or a Satan. As you can see, it is wrong to think of the Devil as a creature with horns and a pitchfork who oversees some underground place of torment. He is really a very powerful, but wicked, angel.
SOURCE
OFWORLDTROUBLES 13
The lie the Devil told Eve worked just as he planned. She believed it and so disobeyed God. And she was able to get her husband to break God’s law also. (Genesis 3:6) The Devil’s claim was that humans can get along without God. He argued that people can rule themselves successfully, without God’s help. The Devil also claimed that he could turn away from God all those who would be the offspring of Adam and Eve. 14
Of course, God could have destroyed Satan right away. But that would not have answered the questions that Satan had raised, questions that could stay in the minds of the angels who were watching. So God allowed time for Satan to try to prove his claims. With what results?15
The passage of time has proved that humans cannot rule themselves successfully without God’s help. Their attempts have failed completely. The people have suffered terribly under the governments of men, which, as the Scriptures show, have been controlled from behind the scenes by the Devil. Also, God’s allowing time has clearly shown that Satan has not been able to turn all persons away from worshiping God. There have always been some who have remained faithful to God’s rulership. You can read in the Bible, for example, that Satan tried, without success, to stop Job from serving God.—Job 1:6-12. 16
Thus the claims of the Devil have been proved false. He most certainly deserves destruction for having started a wicked rebellion against God. Happily, we have now reached the time for God to bring Satan’s rule to an end. Describing the first step in doing this, the Bible tells of an important battle in heaven, which, of course, was not seen or heard by people on earth. Read carefully the following Bible account:17
"War broke out in heaven: Michael [who is the resurrected Jesus Christ] and his angels battled with the dragon, and the dragon and its angels battled but it did not prevail, neither was a place found for them any longer in heaven. So down the great dragon was hurled, the original serpent, the one called Devil and Satan, who is misleading the entire inhabited earth; he was hurled down to the earth, and his angels were hurled down with him. ‘On this account be glad, you heavens and you who reside in them! Woe for the earth and for the sea, because the Devil has come down to you, having great anger, knowing he has a short period of time.’"—Revelation 12:7-9, 12. 18
When did this war in heaven take place? The evidence shows that it happened around the time of World War I, which began in 1914. As the Revelation points out, Satan was removed from the heavens at that time, which means we have been living in his "short period of time" since then. Thus, these are the "last days" of Satan’s world. The increasing of lawlessness, the fear, the wars, the food shortages, the diseases and other distressing conditions we have been experiencing are proof of this fact.—Matthew 24:3-12; Luke 21:26; 2 Timothy 3:1-5.19
Since Satan knows his "short period of time" is about up, he is trying harder than ever before to keep persons from serving God. He wants to take as many persons as he can down into destruction with him. With good reason the Bible describes him as a roaring lion that is looking for someone to eat. (1 Peter 5:8, 9) If we do not want to be caught by him, we need to learn how he attacks and also the ways in which he misleads people.—2 Corinthians 2:11.HOW
SATANMISLEADSPEOPLE 20
Do not think that Satan’s methods of getting people to follow him are always easy to see. He is a master at fooling people. His methods over the thousands of years have, in fact, been so clever that today many people do not even believe that he exists. To them wickedness and evil are simply normal conditions that will always be. Satan operates much like modern-day crime leaders who put on the front of being respectable, but who, behind the scenes, do very wicked things. The Bible explains: "Satan himself keeps transforming himself into an angel of light." (2 Corinthians 11:14) Thus we can expect that his schemes for misleading people would often appear innocent, even beneficial.21
Recall that Satan posed as a friend to Eve. Then he tricked her into doing what she thought would be for her own good. (Genesis 3:4-6) It is the same today. For example, through his human representatives Satan cunningly encourages people to put the interests of human governments even above their service to God. This has given birth to the spirit of nationalism, resulting in terrible wars. In recent times Satan has moved people to bring forth various schemes in their search for peace and security. One of these is the United Nations. But has this created a peaceful world? Far from it! Rather, it has proved to be a means of turning the people’s attention away from God’s arrangement for bringing peace to mankind, his incoming kingdom under Jesus Christ, the "Prince of Peace."—Isaiah 9:6; Matthew 6:9, 10. 22
If we are to receive everlasting life, we need accurate knowledge about God, his King-Son and his kingdom. (John 17:3) You can be sure that Satan the Devil does not want you to have this knowledge, and that he will do all in his power to stop you from getting it. How will he do this? One way is by seeing to it that you receive opposition, perhaps in the form of ridicule. The Bible tells us: "All those desiring to live with godly devotion in association with Christ Jesus will also be persecuted."—2 Timothy 3:12.23
It may be that even close friends or relatives will tell you that they do not like your examining the Scriptures. Jesus Christ himself even warned: "Indeed, a man’s enemies will be persons of his own household. He that has greater affection for father or mother than for me is not worthy of me; and he that has greater affection for son or daughter than for me is not worthy of me." (Matthew 10:36, 37) Relatives may try to discourage you, doing so in all sincerity because they do not know the wonderful truths found in the Bible. But if you give up a study of God’s Word when opposition comes, how will God view you? Also, if you give up, how will those friends and loved ones be helped by you to understand that accurate knowledge of the Bible is of life-or-death importance? Your staying with the things you learn from God’s Word may in time influence them likewise to learn the truth. 24
On the other hand, Satan may be responsible for tempting you to share in some immoral activity, which is displeasing to God. (1 Corinthians 6:9-11) Or it may be that he will cause you to feel that you are too busy to study the Bible. But when you think about it, could there ever be anything more important than obtaining this kind of knowledge? Do not allow anything to stop you from gaining this knowledge that can lead to your receiving everlasting life in paradise on earth!25
The Bible urges: "Oppose the Devil." If you do this, "he will flee from you." (James 4:7) Does this mean that if you resist Satan’s attack he will give up and no longer cause you trouble? No, he will try over and over again to get you to do what he wants. But if you keep on opposing him, he will never be able to get you to take a course in opposition to God. So, be diligent to get the all-important knowledge of the Bible and practice what you learn. This is vital in order to prevent you from being deceived by another of Satan’s means for misleading people, false religion.
Anything, according to this lesson, that puts up an obstacle or hinderance between the potential recruit and the JWs is sent by the devil.
It's very important that you not overtly "oppose" your son's involvement with the JWs, lest you be regarded as a threat. There are ways to do this, but I'm not the expert.
You might want to go to the library and borrow a copy of Steve Hassan's Combatting Cult Mind Control. You can get more information there, that is not JW specific, which you can use to learn different ways to approach your son without him feeling like you are a threat to his cult identity.