Christians are saved by grace alone though faith alone in Christ alone to the glory of God alone.
JWs are “saved” by their faith in the men in Brooklyn, NY through their works (number of hours spent in field service, record of meeting attendance, and moral excellence or law-keeping (not breaking the long list of rules made by those men in Brooklyn).
Christians believe that Jesus is capable of paying for the sins of mankind because he is God manifest in the flesh. Christians believe that the temple of Jesus’ body was torn down and raised again on the third day, thus fulfilling the Scriptures.
JWs, on the other hand, believe that Jesus is the created being, Michael the Archangel, manifest in the flesh, and that although he became a man and underwent physical death, he was not physically raised from the dead.
Christians read Jesus’ words: “Truly, truly, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you have no life in you.“ Therefore, Christians partake in communion.
JWs, on the other hand, have a yearly ritual ceremony in which they publicly reject communion. They make a public spectacle of refusing the New Covenant.
Christians believe that salvation is monergistic - that God works through the Holy Spirit to bring about the salvation of an individual through spiritual regeneration, regardless of the individual's cooperation. It is a free gift that cannot be earned through good works or by refraining from sinning, or anything else that originates from one’s self. Salvation begins and ends with God alone - from God, through God and for God alone.
JWs believe that salvation is synergistic - that salvation is achieved through a combination of human will and divine “undeserved kindness” (I would even argue that JWs lean more toward human will than a number of other synergistic faiths). JWs believe that a person must first clean themselves up and make themselves pleasing to God first before he will accept them. Then they must maintain their own salvation to the very last day, and every time they slip up, they lose their salvation and must clean themselves up again in order to earn back their salvation.
These are just a few differences between Christians and Jehovah’s Witnesses. Can you think of some other major theological differences?
Note: I’m talking about Protestant Christians here.