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.

1 Corinthians 3:18-19 states “Let no man deceive himself. If any man among you seemeth to be wise in this world, let him become a fool, that he may be wise. For the wisdom of this world is foolishness with God.”
Let us not deceive ourselves.
Instead of being wise in our own eyes, let us be spiritually wise and that means fear the Lord and depart from evil (Proverbs 3:7). The Fear of the Lord is the beginning of wisdom (Proverbs 9:10). To fear God is not only the beginning of wisdom, but it is also the whole duty of man and that is the conclusion of the whole matter (Ecclesiastes 12:13).
Let us not be wise in our own eyes and deceive ourselves.

1 Corinthians 3:18-23 (KJV)
18 Let no man deceive himself. If any man among you seemeth to be wise in this world, let him become a fool, that he may be wise.
19 For the wisdom of this world is foolishness with God. For it is written, He taketh the wise in their own craftiness.
20 And again, The Lord knoweth the thoughts of the wise, that they are vain.
21 Therefore let no man glory in men. For all things are your’s;
22 Whether Paul, or Apollos, or Cephas, or the world, or life, or death, or things present, or things to come; all are your’s;
23 And ye are Christ’s; and Christ is God’s. 

Ecclesiastes 12:13-14 (KJV)
13 Let us hear the conclusion of the whole matter: Fear God, and keep his commandments: for this is the whole duty of man.
14 For God shall bring every work into judgment, with every secret thing, whether it be good, or whether it be evil.