Beware of practicing your piety before men in order to be seen by them; for then you will have no reward from your Father who is in heaven. Matt. 6:1, RSV.
With Matthew 6:1-18 Jesus shifts the center of His discussion of kingdom principles from a Christian's righteousness to a believer's piety. He selects almsgiving (verses 2-4), praying (verses 5, 6), and fasting (verses 16-18) to illustrate principles that we can apply to all acts of religious piety. It is frightening to believe that we can go off the track in such religious activities as prayer and giving to God, but Jesus says we can.
In essence, He is teaching that we didn't fully get rid of sin when we left our nasty way of life. To the contrary, sin is more than eager to follow us to church.
His pattern is the same in each illustration. First comes a description of the false way of piety, which focuses on public display of the "worshiper's" holiness. He uses the word "hypocrites" in each illustration. In Greek "hypocrite" means an actor on the stage. Applied to religious experience in Matthew 6, a hypocrite is one who wears a false face. He or she is pretending to honor God, while really glorifying self. Such people, Jesus asserts, have already had their reward. The second half of each illustration suggests a proper way to fulfill the obligation (e.g., pray in secret). In each case the central idea is that motivation for devotion should be grounded in a person's relationship with the Father rather than a desire to look good. All three illustrations close with a statement that God will reward the faithful.
In Matthew 6:1-18 Jesus brings us face-to-face with "vegetarian sins," sins that look so good because they are tied to religious practice, the sins of the Pharisees of every generation.
Such sins are deceptive and deadly because they capture us unaware--they make us feel so religious, so right. But that is where deceptiveness comes in. They lead us to think that we are clean when we are still filled with the rotten core of sin--prideful self-sufficiency and self-centeredness.
Jesus, dear friend, wants to save us even from our religious sins, even from our spiritual pride, even from feeling good about our prayer life.
And how does He propose to do this? The same way He does for prostitutes and drug dealers. He wants our prideful spirit to fall at the foot of the cross and be crucified.
But beyond crucifixion of our self-righteous pride, Jesus wants to engineer our rebirth through life in the Spirit. The good news is that He is able if we are willing.