First, sin may bring doubts. Sin breaks the chain of faith. Sin weakens your life. Sin blinds the eyes. Sin destroys your ability to lay hold upon truth.
Sin tries to put the blame on another.
Whenever you allow sin to invade your life, then, my friend, you can be sure that you will soon begin to have doubts. It matters not what the sin may be. It may be a sin of unfaithfulness. It may be a sin of falsehoods. It may be a sin of stealing.