So that people who need an invisible crutch to help them through life learn to accept full responsibility for all their actions rather than having what they see as the get out of jail card of murdering, raping and mutilating in their God's name.
To help bring an end to all forms of slavery, oppression and class systems designed to empower an elite minority while disenfranchising and devaluing the vast majority throughout the world.
The world would be a better place if people acted in ways that good personal moral standards replaced those that were forced upon them, which they felt compelled to uphold not through belief in them but simply through blind adherence, indoctrination and accident of birthplace.