Secular Reasons for Spiritual Success
The core secular reason for the success of Christianity can only be that Christianity portrays and accurate model, and accurate account, an accurate representation, of human life and its place in the universe.
The Gnostic model, like the Marxist model, portrays all life as a darwinian struggle between the enlightened and the benighted. There is nothing but a struggle for power. There’s no love between husband and wife, no mutual self-interest between employer and employee, no possibility of Amity between the races. There’s no justice between high and low, rich and poor. That’s not accurate.
Gnosticism says truth as a private matter, esoteric, not open to public debate or verification. That’s not accurate.
Marxism portrays man as collective. That’s not accurate.
Christianity says the first shall be last and the last shall be first. In other words the humble view is the wise and honest view. That is accurate. Read any history book.
Christianity says self-sacrificing love is more satisfying than selfishness. That is accurate. Read any primer on psychology.
Christianity says that what the world calls torture, death, defeat is glory and triumph. That is accurate. Read any dialogue of philosophy. And so on and so on.