The biggest difference between Jehovah’s Witnesses and orthodox Christianity is that the Watch Tower Society teaches that Jesus was not God. They reject the Christian teaching that Jesus existed as God before, during, and after his incarnation
The New World Translation, which is used by Jehovah’s witnesses changes the wording in John 1:1 from “The Word was God” to The Word was a god.” It can be difficult to argue from Greek grammar with someone who most likely doesn’t know Greek themselves. However, if you read just a bit further down you will find sufficient proof for the deity of Christ in verse 3 in the New World Translation.
“All things came into existence through him, and apart from him not even one thing came into existence.”
John 1:3 NWT
Here we see that everything created was created by the Word, ie Jesus.
I ask my JW friends a question here, “Is there anything that Jesus didn’t create?” They usually answer with “No” and they are right. According to John 1:3, Jesus created everything and there is nothing that was created that he didn’t created.
The next question to ask is, “Was Jesus created?” If they answer according to their doctrine they must say “yes.”
“God created Jesus before creating Adam. In fact, God created Jesus and then used him to make everything else, including the angels.”
Watchtower Magazine, March 2013
Here we can easily point them back to John 1:3 in their own Bibles and show them that their own Bibles contradict the teaching of the Watch Tower Society. If Jesus created everything that has been created, then Jesus couldn’t have created himself and Jesus can’t be a created being. Jesus is the Creator, He is Jehovah!