Protestantism often leads to atheism because the Protestantism preaches about God, who does not fulfill His promises.
Jesus promised to create the church
and the gates of hell shall not prevail against it. The Protestants are taught that the gates of hell prevail against it with huge success - so huge, that  took its "Reformation."

 It is my strong opinion that the Catholics are the only Christians who can afford the luxury of simple faith in God. I do not know why this is happening, but any attempt to create a non-Catholic theology generate numerous conflicts between faith and reason. Either you disconnect to logic, to maintain peace of mind, or you have to create an arsenal of evidences for your faith, and then constantly afraid that your proofs are wrong, or you lose faith to stay honest  with yourself.  During the protestant period of my life I have become skilled in religious rhetoric, and terribly tired of it, so that I desperately wanted a simple faith of the Breton peasant.