2 Corinthians 3

Paul pointed out that his credentials did not come from men - not from himself and not from any other man. God had given Paul his credentials in the form of the many lives touched in the places where he preached. The new covenant brought by Christ had replaced the old one given to Moses, but some couldn't see past the old laws.

The only source of authority for preaching the word of God is God Himself. When we look at people who claim to be speaking for God, we need to look for the signs in their life that they are acting on behalf of the Lord and not themselves. God's true servant will bear His mark on the things they do.