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.
Galatians 6:3 states that the one who thinks of himself as something, when he is nothing, deceives himself. The dictionary defines a narcissist as a person who is overly self-involved, and often vain and selfish. Biblically, narcissism is referred to as selfishness.
Let us not deceive ourselves.
Let us in lowliness of mind esteem each other better than ourselves. (Philippians 2:3). We must put on humbleness of mind (Colossians 3:12) as is the mind of Christ (Philippians 2:5-7), who being God, considered it robbery to be made equal with God, and made himself of no reputation, and took on the form of a servant humbled himself to become obedient unto death, even the death on the cross.
Let us not be a narcissist and deceive ourselves.
Galatians 6:3 (KJV)
3 For if a man think himself to be something, when he is nothing, he deceiveth himself.
Colossians 3:12-13 (KJV)
12 Put on therefore, as the elect of God, holy and beloved, bowels of mercies, kindness, humbleness of mind, meekness, longsuffering;
13 Forbearing one another, and forgiving one another, if any man have a quarrel against any: even as Christ forgave you, so also do ye.
Philippians 2:3-11 (KJV)
3 Let nothing be done through strife or vainglory; but in lowliness of mind let each esteem other better than themselves.
4 Look not every man on his own things, but every man also on the things of others.
5 Let this mind be in you, which was also in Christ Jesus:
6 Who, being in the form of God, thought it not robbery to be equal with God:
7 But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men:
8 And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross.
9 Wherefore God also hath highly exalted him, and given him a name which is above every name:
10 That at the name of Jesus every knee should bow, of things in heaven, and things in earth, and things under the earth;
11 And that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father.