It is one thing to be deceived by someone else, but to be deceived by oneself is quite another. The Bible counsels us to be wary against self-deception and informs us of the conditions in which one is self-deceived.
James 1:26 state that if any man among you seems to be religious, and bridleth not his tongue, deceives his own heart and his religion is vain. A word that is aptly spoken is like apples of gold in pictures of silver (Proverbs 25:11) and a wholesome tongue is a tree of life: but perverseness therein is a breach in the spirit (Proverbs 15:4).
Let us not deceive ourselves.
Let us put the bit and bridle to our tongue so that our lives may be in the direction that God wants us to be and like it was on prophet Samuel, let the Spirit of the Lord be in us and his word always be on our tongue (2 Samuel 23:2).
Let us not be unbridled and deceive ourselves.
James 1:26 (KJV)
26 If any man among you seem to be religious, and bridleth not his tongue, but deceiveth his own heart, this man’s religion is vain.
2 Samuel 23:2 (KJV)
2 The Spirit of the LORD spake by me, and his word was in my tongue.