In your opinion what causes christians to believe in Jesus

[John 6IX Breezy]

Christians go by the Bible when it comes to how God is defined, and what kind of relationship is possible with him. 

Yes, but the Bible doesn't say much about God's nature, God simply is. That's because the Bible is written from the perspective of individuals who say they interacted with him, and so the focus is on the interaction. If you tell me the story of how you met your partner, I wouldn't expect you to break down their biology and genetics, I would expect you to focus on the event itself.