John_ChrysostomFor whom was Jesus baptised, if this was done not for repentance, nor for the remission of sins, nor for receiving the gifts of the Spirit?

[…] When John said: I have need to be baptised of Thee, and Thou art come to me?—He answered thus: Stay now, for thus it becometh us to fulfil every righteousness (Matthew 3:14-15).

[…] What does He mean: To fulfill every righteousness? By righteousness is meant the fulfillment of all the commandments, as is said: Both were righteous, walking faultlessly in the commandments of the Lord (Luke 1:6).

Since fulfilling this righteousness was necessary for all people, but no one of them kept it or fulfilled it, Christ came then and fulfilled this righteousness.

And what righteousness is there, someone will say, in being baptised? Obedience for a prophet was righteous.

As Christ was circumcised, offered sacrifice, kept the sabbath and observed the Jewish feasts, so also He added this remaining thing, that He was obedient to having been baptised by a prophet.

[…] If obedience to God constitutes righteousness, and God sent John to baptise the nation, then Christ has also fulfilled this along with all the other commandments.

Consider, that the commandments of the law is the main point of the two denarii (see Luke 10:35). The human race needed to pay this debt [i.e. observing the commandments] but did not pay it…, and so is embraced by death. Christ…paid the debt…and seized from it those who were not able to pay.

Wherefore He does not say: It is necessary for us to do this or that, but rather, To fulfill every righteousnessIt is for Me, being the Master, says He, proper to make payment for the needy.

[…] Wherefore also the Spirit did descend as a dove: because where there is reconciliation with God, there also is the dove.

So also in the ark of Noah the dove did bring the branch of olive—a sign of God’s love of mankind and of the cessation of the flood.

And now in the form of a dove, and not in a body…the Spirit descended, announcing the universal mercy of God and showing with it, that the spiritual man needs to be gentle, simple and innocent, as Christ also says: Except ye be converted and become as children, you shall not enter into the Heavenly Kingdom (Mt 18:3).

But that ark, after the cessation of the flood, remained upon the earth; this ark, after the cessation of wrath, is taken to heaven, and now this Immaculate and Imperishable Body is situated at the right hand of the Father.

John Chrysostom (c.347-407): Discourse on the Day of the Baptism of Christ @ Pravoslavie.