During the past century, Christianity experienced a meteoric rise. Now it has stalled in the West. Islam is taking parts of the world by storm. It has the same problem as Christianity. For every convert, someone is stolen by a breakaway group.
During the last Presidential election, there was public discussion as to whether candidate Romney’s branch of Christianity was “real” or not. As we all know, the arguments over which is right, Catholics, Protestants or a thousand other versions is “the truth” go on and on.
It seems to me there is a need for religion by a slice of human kind. That is a bucket that must be filled. It is filled with the faiths each culture comes up with. The various faiths are generated by the various cultures they come from. Were this not the case, we would not see people in India being majority Hindu and the U. S. majority Christian.
Within the Christian faith, we see pictures of a Jesus with racial features of the locals. No one religion will dominate the world so long as diverse the cultures that invent them vary so widely.
The Jewish faith was splintered before Christianity. As soon as Christianity was invented, it too began splintering and has continued to do so.
One explanation is the cultures that invented the religions themselves split up in subtle ways. The North and South, East and West are all reflected in both the cultures and religions they spawn.