If you want the WTS position on this, here is something that may illustrate their position.
*** w03 9/1 One True Christian Faith—A Reality ***
The Christian Congregation Corrupted
Soon after the death of the apostles, apostate teachers from within the congregation began to take control of it. They spoke "twisted things to draw away the disciples after themselves." (Acts 20:29, 30) As a result, many Christians ‘fell away from the faith.’ They were "turned aside to false stories."—1 Timothy 4:1-3; 2 Timothy 4:3, 4.
By the fourth century C.E., says TheNewDictionaryofTheology, "Catholic Christianity had become the official . . . religion of the Roman Empire." There was a "coalescence of ecclesial and civil society"—a merging of Church and State that was diametrically opposed to the beliefs of the early Christians. (John 17:16; James 4:4) The same source states that in time, the whole structure and nature of the church, as well as many of its fundamental beliefs, was changed radically "under the influence of a curious and thoroughly unhealthy combination of O[ld] T[estament] and neoplatonic models." As predicted by Jesus Christ, his genuine disciples were hidden from sight as counterfeit Christians flourished.
Jesus’ listeners knew how difficult it was to tell genuine wheat from weeds, such as poisonous bearded darnel, which during the growing season has an appearance much like that of wheat. So Jesus was illustrating that for a while, it would be difficult to distinguish true Christians from the counterfeit variety. This does not mean that the Christian congregation ceased to exist, for Jesus promised to continue to guide his spiritual brothers "all the days until the conclusion of the system of things." (Matthew 28:20) Jesus said that the wheat would continue to grow. Even so, through the ages, genuine Christians—individually or in groups—no doubt did their best to adhere to Christ’s teachings. But they no longer made up a clearly identifiable, visible body, or organization. They were certainly not identical with the visible apostate religious system that throughout history brought nothing but disgrace and dishonor to the name of Jesus Christ.—2 Peter 2:1, 2.
"The Man of Lawlessness Gets Revealed"
The apostle Paul foretold something else that would mark this counterfeit religious system. He wrote: "Let no one seduce you in any manner, because [Jehovah’s day] will not come unless the apostasy comes first and the man of lawlessness gets revealed." (2 Thessalonians 2:2-4) This "man of lawlessness" is none other than the clergy class that exalted itself into a ruling position over the "Christian" congregation.
The apostasy started in the apostle Paul’s day. It accelerated once the apostles died and their restraining influence disappeared. It would be marked, said Paul, by "the operation of Satan with every powerful work and lying signs and portents and with every unrighteous deception." (2 Thessalonians 2:6-12) How accurately that describes the activities of so many religious leaders throughout history!
In support of their claim that Roman Catholicism is the one true church, Catholic leaders say that their bishops have "a life-giving contact with the original apostles by a current of succession which goes back to the beginning." In truth, this claim of apostolic succession has no historical or Scriptural basis. There is no credible evidence that the church system that arose following the death of Jesus’ apostles was ever directed by God’s holy spirit.—Romans 8:9; Galatians 5:19-21.
And what of the other churches that sprang up following the so-called Reformation? Did they return to the model of the early Christian congregation? Did they restore the purity of the original Christian congregation? It is true that following the Reformation, the Bible became available to many of the common people in their own language. Yet, history shows that these churches continued to teach erroneous doctrines.—Matthew 15:7-9.
Note this, however. Jesus Christ definitely foretold that his one true congregation would be restored during what he called a conclusion of a system of things. (Matthew 13:30, 39) The fulfillment of Bible prophecies shows that we are now living in that time. (Matthew 24:3-35) That being true, each of us needs to ask, ‘Where is that one true church?’ It ought to become more and more clearly identifiable.
Maybe you feel that you have already found that church, or congregation. It is important that you make sure. Why? Because as in the first century, there can be only one true church. Have you taken the time to make sure that your church closely conforms to the pattern set by the first-century Christian congregation and that it loyally adheres to the teachings of Jesus Christ? Why not examine this now? Jehovah’s Witnesses will be happy to help you to do just that.—Acts 17:11.
[Footnotes]
Further information regarding the identity of "the man of lawlessness" can be found in TheWatchtower, February 1, 1990, pages 10-14.
See the chapter "The Reformation—The Search Took a New Turn" in the book Mankind’sSearchforGod, pages 306-28, published by Jehovah’s Witnesses.