Cyril-of-JerusalemJesus sanctified Baptism by being Himself baptized.

[…] He was baptized not that He might receive remission of sins, for He was sinless.

Being sinless, He was baptized, that He might give to them that are baptized a divine and excellent grace.

Since the children are partakers of flesh and blood, He also Himself likewise partook of the same (Heb. 2:14).

This was so that, having been made partakers of His presence in the flesh we might be made partakers also of His Divine grace.

Thus Jesus was baptized, that thereby we again by our participation might receive both salvation and honour.

According to Job, there was in the waters the dragon that draweth up Jordan into his mouth (Job 40:23).

Since, therefore, it was necessary to break the heads of the dragon in pieces (Ps. 74:14), He went down and bound the strong one in the waters, that we might receive power to tread upon serpents and scorpions (Luke 10:19).

The beast was great and terrible.  No fishing-vessel was able to carry one scale of his tail (Job 40:26 [LXX]). Destruction ran before him (Job 41:13), ravaging all that met him.

The Life encountered him, that the mouth of Death might henceforth be stopped, and all we that are saved might say, O death, where is thy sting?  O grave, where is thy victory (1 Cor. 15:55)?

The sting of death is drawn by Baptism. For you go down into the water, bearing your sins, but the invocation of grace, having sealed your soul, does not allow you afterwards to be swallowed up by the terrible dragon.

Having gone down dead in sins, you come up quickened in righteousness.  For if you have been united with the likeness of the Saviour’s death (Rom. 6:5), you shall also be deemed worthy of His Resurrection.

Jesus took upon Him the sins of the world, and died that, by putting sin to death, He might rise again in righteousness.

Similarly, you, by going down into the water, and being in a manner buried in the waters, as He was in the rock, are raised again walking in newness of life (Rom. 6:4).

Moreover, when you have been deemed worthy of the grace, He then gives you strength to wrestle against the adverse powers.

After His Baptism He was tempted forty days (not that He was unable to gain the victory before, but because He wished to do all things in due order and succession.

So you likewise, though not daring before your baptism to wrestle with the adversaries, after you have received the grace and are henceforth confident in the armour of righteousness (2 Cor. 6:7), must then do battle, and preach the Gospel, if you will.

Cyril of Jerusalem (c. 313-386): Catechetical Lectures 3, 11-13.