BOASTING
Most people do not openly boast about the things they do. Not so with religious people. Religion creates an environment in which boasting about religion is encouraged. They boast of their religious status in what they wear, what they say and what they do. That is why Jesus condemned the Pharisees about their very public religious behaviors.

The apostle Paul discusses boasting in the following scriptures:

2 Corinthians 10: Now I, Paul, myself urge you by the meekness and gentleness of Christ -I who am meek when face to face with you, but bold toward you when absent!  2 I ask that when I am present I need not be bold with the confidence with which I propose to be courageous against some, who regard us as if we walked according to the flesh.  3 For though we walk in the flesh, we do not war according to the flesh, 4 for the weapons of our warfare are not of the flesh, but divinely powerful for the destruction of fortresses.  5 We are destroying speculations and every lofty thing raised up against the knowledge of God, and we are taking every thought captive to the obedience of Christ,  6 and we are ready to punish all disobedience, whenever your obedience is complete. 
COMMENTARY: See DEMOLISHING STRONGHOLDS.
7 You are looking at things as they are outwardly. If anyone is confident in himself that he is Christ’s, let him consider this again within himself, that just as he is Christ’s, so also are we. 
COMMENTARY: Religious people always judge others according to outward evidence of religiosity. This contrasts with God who always looks at and tests the heart. He is looking for evidence of a pure heart.
8 For even if I  boast somewhat further about our authority, which the Lord gave for building you up and not for destroying you, I will not be put to shame,  9 for I do not wish to seem as if I would terrify you by my letters.  10 For they say, “His letters are weighty and strong, but his personal presence is unimpressive and his speech contemptible.”  11 Let such a person consider this, that what we are in word by letters when absent, such persons we are also in deed when present.  12 For we are not bold to class or compare ourselves with some of those who commend themselves; but when they measure themselves by themselves and compare themselves with themselves, they are without understanding. 
COMMENTARY:
13 But we will not boast beyond our measure, but within the measure of the sphere which God apportioned to us as a measure, to reach even as far as you.  14 For we are not overextending ourselves, as if we did not reach to you, for we were the first to come even as far as you in the gospel of Christ;  15 not boasting beyond our measure, that is, in other men’s labors, but with the hope that as your faith grows, we will be, within our sphere, enlarged even more by you,  16 so as to preach the gospel even to the regions beyond you, and not to boast in what has been accomplished in the sphere of another
COMMENTARY:
17 But HE WHO BOASTS IS TO BOAST IN THE LORD.  18 For it is not he who commends himself that is approved, but he whom the Lord commends.
COMMENTARY: Religious people interpret verse 17 as license to boast about their relationship with God. But they ignore verse 18 which says that self-commendation does not count with God. It also ignores the fact that God does not look at the outer person, including what he/she says, but looks only at the heart.