"Repent" (Matt. 3:2).
"Repent" is the first great call of the Gospel. It is the first word from the mouth of John the Baptist. This could be why he wore what he did (camel's hair) and ate what he did (locusts and wild honey): to show and teach that there is something more important - vastly so - than food and clothing (Matt. 6:25).
Grammatically speaking, "Repent" is an imperative. A command, an order. Repentance is non-optional. The only option is to disobey. Grammatically speaking, "Repent" is a "present" imperative. It means: "Be repenting, keep on repenting, don't stop repenting!" It means a life of repentance.
Spiritually speaking, repentance is imperative. If we are to "seek first the kingdom of God" (Matt. 6:33), we will find it only through repentance.
The 1530 Augsburg Confession contains a terse definition of repentance worth dusting off: "True repentance is nothing else than to have contrition and sorrow, or terror, on account of sin, and yet at the same time to believe the Gospel and absolution (namely, that sin has been forgiven and grace has been obtained through Christ), and this faith will comfort the heart and again set it at rest. Amendment of life and the forsaking of sin should then follow, for these must be the fruits of repentance, as John says, 'Bear fruit that befits repentance' (Matt. 3:8)."
Now I know that repentance may seem out of place a couple of weeks before Christmas. Like John himself, repentance is never in vogue.
Yet only the repentant will truly "find the babe wrapped in swaddling clothes, lying in a manger" (Luke 2:12) on Christmas Night.