Jesus sanctified baptism when He Himself was baptized. If the Son of God was baptized, can anyone who scorns baptism pretend to piety? Not that He was baptized to receive the remission of sins—for He was without sin—but being sinless, He was nevertheless baptized, that He might impart grace and dignity to those who receive the sacrament. For, “since the children share in flesh and blood, so he in like manner has shared in these,” that we, sharing His incarnate life, might also share His divine grace. So Jesus was baptized that we, in turn, herein also made partakers with Him, might receive not only salvation, but also the dignity. The dragon, according to Job, was in the water, he who received the Jordan in his maw. When, therefore, it was necessary to crush the heads of the dragon, descending into the water, He bound the strong one, that we might receive the “power to tread upon serpents and scorpions.” It was no ordinary beast, but a horrible monster. No fishing ship could last under a single scale of his tail; before him stalked Destruction, ravaging all in her path. But Life came running up, that the maw of Death might be stopped and all we who were saved might say: “O death, where is thy sting? O grave, where is thy victory?” Baptism draws death’s sting.
For you go down into the water bearing your sins, but the invocation of grace, placing a seal upon your soul, makes you proof against the dragon’s maw. Though dead in sin when you went down, you will come up vivified in justice. For, if you have been planted together in the likeness of the death of the Savior, you shall be counted worthy of His Resurrection also. For just as Jesus died, taking upon Himself the sins of the whole world, that by slaying sin He might rise again in righteousness, so you, also, after entering and being as it were buried in the water, as He was in the rock, are raised up again to walk in newness of life.
Then, after you have been vouchsafed the grace, He gives you the strength to struggle with the enemy powers. For just as He was tried for forty days after His baptism—not that He was unable to conquer sooner, but because He wished to accomplish all things in due order and sequence—so do you also, who before your baptism dared not close with your adversaries, from the moment of receiving the grace, trust henceforth in the armor of justice, do battle, and, if you will, preach the Gospel.
St. Cyril of Jerusalem, Catechetical Lectures III.11–13
Locus Communis 