We learn from the Gospel parable [the story of the prodigal son] that for successful and fruitful repentance, a man needs to provide on his part: seeing his own sin, recognizing it, repenting of it, and confession of it.
God sees a person who has made this pledge in heart while he is yet a long way off; He sees him and runs to meet him, embraces and kisses him with His grace.
No sooner had the penitent pronounced his confession of his sin than the merciful Lord commanded the slaves—the servants of the altar and the holy Angels—to clothe him in bright garments of purity;
to place his ring upon his finger as a testimony of his renewed union with the Church both on earth and in heaven;
and to place shoes upon his feet, so that his actions would be protected from spiritual thorns by steadfast ordinances, for that is the meaning of the shoes—Christ’s commandments.
To complete the action of love, a feast of love is held for the returned son, for which a fatted calf is killed.
This feast signifies the Church feast to which the sinner is invited once he has made his peace with God—the spiritual, incorruptible food and drink—Christ—promised long ago to mankind, prepared through the unspeakable mercy of God for fallen man from the very moment of his fall.
[…] What more consoling news could there be for a sinner who stands trembling before the doors of repentance than this news about the Heavenly Father’s infinite and unspeakable mercy for repentant sinners?
This mercy is so great that it amazed the very Angels—the first-born sons of the Heavenly Father, who had never transgressed a single commandment of His.
Their bright, lofty minds could not fathom the unfathomable mercy of God for fallen mankind.
They needed a revelation from on High regarding this subject, and they learned from this revelation that it is meet for them to make merry, and be glad, for their lesser brother—the human race—was dead, and is alive again; and was lost, and is found, through the Redeemer.
There is joy in the presence of the angels of God even over one sinner that repenteth.
[…] May our rejoicing be endless! May it be joined to the rejoicing of the holy Angels of God! May the joy of Angels and men be fulfilled and made perfect through their fulfilling the will of the Heavenly Father!
For, it is not the will of your Father which is in heaven, that one of these little ones—human beings, deprecated and humiliated by sin—should perish (Mt. 18:14).
Ignatius Brianchaninov (1807–1867; Russian Orthodox): Instruction on the Sunday of the Prodigal Son, on Repentance, translated by Nun Cornelia Rees @ Pravoslavie