Contrapositive

The contrapositive is logically equivalent to the original statement. Instead of directly proving "God exists → objective morality exists," we prove its contrapositive: "If there is no God, there can be no objective morality." Without a transcendent moral Lawgiver, moral claims reduce to subjective preferences or social conventions. But we recognize objective moral truths: torturing innocents is truly wrong, not just unpopular. Since objective morality exists, its contrapositive guarantees God exists.

This is proof by contrapositive: instead of proving P → Q directly, we prove the logically equivalent ¬Q → ¬P. The moral argument demonstrates that atheism cannot ground objective morality, so the existence of objective morality implies theism.