It’s likely there’s no way to prove with 100% certainty that our moral convictions can only come from God, therefore proving His existence. We suggest that there’s no individual argument that can prove God’s existence with absolute certitude. However, those who don’t believe in God have much to explain away when it comes to moral law.
The fact that all us have an innate sense of moral values that transcends what we actually do, and what the world is actually like, is best explained by
God created us with a sense of what we ought to do. Our experience is in alignment with what we would expect to be true, if God did exist. Our sense of moral obligation, which is one of the most undeniable things about us, points to the existence of God.