Mainly christians....I myself am not religious and dont have ties to any religion

I want you to attempt to explain to me how christians believe that Jesus was the son of god, but at the same time he is also god. We recently came upon this topic in my western civ class and it just makes no sense to me. Although christians today may not believe that, when christianity first started around 66 A.D. they believed that Jesus was the son of God, but at the same time he was god. Also the fact that Jesus himself preached that he was not only the son of god, but also god, makes absolutely no sense to me.