On the assumption that this is true, very few people found out about this directly - i.e. direct interaction with Jesus - virtually everyone found out through interactions with other humans.
That only a few had direct interaction is down to God incarnating as a person. Yes a lot of people have the full history due to interactions with other humans. But to argue that Christianity arises through that is incorrect. For instance you have probably received the Gospel and the intellectual and historical details and yet Christianity does not seem to have appeared in you. The point being that there must be more going on that you seem to be discounting.
Let's look at the resurrection - christians think this to be perhaps the most remarkable thing ever to have happened. Why didn't god tell people all around the world when it happened, including people in the americas, australia etc, etc. He could have sent angels - he seemed to be comfortable to do this when Jesus was born - e.g. to Shepherds - sending them a very clear message about something remarkable that had just happened. So why not communicate in the same way to tell people across the world directly about the resurrection?
People believe in the resurrection rather than merely know of it because they encounter Christ. Again because of god's action in incarnating as a person only a few are going to experience the physical resurrection, empirically and historically at first hand.
How is being told by angels not second hand. If you are going to say god should have told people by angelic messenger just after the resurrection you may as well go onto the question of why there aren't angels telling people all the time.....To this we can say how do we
know people aren't contacted this way?, who'd believe it?, would we get preoccupied with angels rather than Christ.
Again how does this theological point of view(what God should have done) sit with your atheist point of view that God has told no one anything?
