Because most other religions have the same stories and everyone is to afraid to read on "fear" of Satan.
God is love and truth and Satan is fear and lies.
There is a reason that Alexandria was burned, book burnings were common and the nazis destroyed so much art.
Christ by most interpretations was another Buddha (before you throw Satan understand what a Buddha is)
The last Buddha before him came with 10 teachings (oddly the same as the Ten Commandments)
The 3 wisemen draw a lot of parallels to the Asian secret societies that track bodhi and Buddha incarnations (who bring items from last incarnations to help that person remember)
The "lost years" were spent in the Far East training under these societies, a lot of people remember Christ in the Far East even going so far as making him a patron Saint of the area.
A lot of evidence suggests Jesus was a vegetarian
Meditation and prayer are almost the same concepts and the Bible talks of Jesus meditating in a cave.
Jesus never wanted anyone to formulate a religion from him it's evident by his all of teachings and the schisms!
"Heresy" is invented by man and the words of god have been so twisted by man despite him giving us ten rules not open to our own interpretation main one being:
Thou shalt not kill
I didn't happen to see fine print that said (unless they are an animal, the earth, a heretic, another race, color or religion or they start the fight or I really feel god owes me this land so I'm going to take it, or some "holy man" who isn't a Buddha (Christ) or bodhi (Saint) decided it was gods law and you were scum if not followed.)
Church also has a terrible track record through history of not following any of the commandments and being EXTREMELY corrupt.
"Do as they say not as they do"
You research and make the calls.
God is love and he wants you to know all.
And to answer your question:
Atheists are only atheists because they are ignorant as the schism religious groups. Ignorance doesn't fight ignorance. It just forms hate.
Love fights hate.
If everyone knew the truth there would be no atheists and one religion. But the world couldn't have that now could it? How else would satan have his daily fill of murder and hatred/vitrol?