(Read Matthew 3:1-6)

After Malachi there was no prophet until John the Baptist came. He appeared first in the wilderness of Judea. This was not an uninhabited desert, but a part of the country not thickly peopled, nor much enclosed. No place is so remote as to shut us out from the visits of Divine grace. The doctrine he preached was repentance; “Repent ye.” The word here used, implies a total alteration in the mind, a change in the judgment, disposition, and affections, another and a better bias of the soul. Consider your ways, change your minds: you have thought amiss; think again, and think aright. True penitents have other thoughts of God and Christ, sin and holiness, of this world and the other, than they had. The change of the mind produces a change of the way. That is gospel repentance, which flows from a sight of Christ, from a sense of his love, and from hopes of pardon and forgiveness through him. It is a great encouragement to us to repent; repent, for your sins shall be pardoned upon your repentance. Return to God in a way of duty, and he will, through Christ, return unto you in the way of mercy. It is still as necessary to repent and humble ourselves, to prepare the way of the Lord, as it then was. There is a great deal to be done, to make way for Christ into a soul, and nothing is more needful than the discovery of sin, and a conviction that we cannot be saved by our own righteousness. The way of sin and Satan is a crooked way; but to prepare a way for Christ, the paths must be made straight, Zechariah 13:1.

For a more detailed summary select the link below.

Matthew 3 Bible Commentary – Matthew Henry (concise) (christianity.com)

Matthew 3:2

² “Repent, for the Kingdom of Heaven is at hand!”