Even if angels stand next to you, you wouldn't believe it. Even if God is sitting next to you, you wouldn't believe it. Even if Jesus is in front of you and say, I am Jesus, you wouldn't believe it.
If you ever read the bible, faith is always the ingredient in the relationship with God. When Noah built the Ark, he did it through faith. Noah was telling the townspeople what's to come and they were factual people, mind you, and all of them ended up drowning except Noah and his family.