Post-Constantine, when men compromised the true Kingdom with kingdoms of this earth.
There wasn't a fall of Christianity. It is still a popular religion.
the fall of constantinople did not effect christianity
If you mean where did Christianity begin, it began in Israel.
Christianity began in the 1st century AD in Jerusalem.
somewhere
where did Christianity begin?
indai
There are no secrets of or in Christianity. If you are asking what is the secret of success in Christianity that would be fully trusting in the Lord and begin obedient to Him.
Christianity.
Christianity
Isreal. Specifically Jeruselum.
By the time of the fall of the Western Empire, Christianity was well established as the state religion and other religions were forbidden. Naturally, there was no prohibition on Christianity, and persecution of non-Christians was accepted practice.