Many people believe Jesus to be God because of what He said about Himself and because of what His life revealed. 

According to the New Testament biographies of Jesus seen in the Gospels, Jesus claimed to be the Son of God and the Son of man. He was also one with God which makes Him God. He claimed to be “I am that I am”.

Jesus was one with God the Father. More info here.

Read more details here.

And more details here.

More info here.

Jesus came from outside of this world. Read about it here.