All Power, the Triune Name, and "I Am With You"
Matthew 28:18-20, the Great Commission, as the early church read it
The Gospel of Matthew ends on three pillars: all authority given to the risen Christ, the command to make disciples and baptize them into the one name of Father, Son, and Holy Spirit, and the promise of His presence to the end of the age. The Fathers read this baptismal command as one of the clearest statements of the Trinity in all of Scripture, three Persons, one Godhead, and they used it directly against those who divided or collapsed the Three. Their words below, with a plain restatement.
Each Father's words are verbatim and attributed (Catena Aurea, public domain, lightly corrected for scan errors). The box marked "In plain terms" is our own restatement, never the Father's words.
Matthew 28:18 · KJVAnd Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth.
"Power is given to Him, Who but a little before was crucified, Who was buried, but Who afterwards rose again… Power is given in heaven and in earth, that He who before reigned in heaven, should now reign on earth by the faith of the believers."
St. Jerome"This He speaks not from the Deity coeternal with the Father, but from the Humanity which He took upon Him… The Son of God conveyed to the Son of the Virgin, the God to the Man, the Deity to the Flesh, that which He had ever together with the Father."
St. Bede (citing Chrysologus)The One claiming all authority is the very One who was crucified and buried days before. As God the Son He never lacked that authority; what is "given" is given to Him as the risen man, so that the One who always reigned in heaven now reigns on earth too, through the faith of those who believe.
Matthew 28:19 · KJVGo ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:
"They first teach all nations, and when taught dip them in water… 'In the name of the Father, the Son, and the Holy Ghost,' that they whose Godhead is one should be conferred at once, to name this Trinity being to name One God."
St. Jerome"And though some one… undertake to baptize in such sort as to omit one of these names, therein contradicting Christ Who ordained this for a law, his baptism will effect nothing… From these words we gather how undivided is the substance of the Trinity, that the Father is verily the Father of the Son, and the Son verily the Son of the Father, and the Holy Spirit the Spirit of both the Father and the Son."
St. Jerome"For what part of the salvation of men is there that is not contained in this Sacrament? All things are full and perfect, as proceeding from Him who is full and perfect… The Son is the Offspring of the Unbegotten, One of the One, True of the True, Living of the Living, Perfect of the Perfect… the Image of the Unseen God… Neither can the Holy Spirit be separated from the confession of the Father and the Son."
St. Hilary of PoitiersNotice the grammar Jesus chose: not "in the names," but "in the name" (singular) of Father, Son, and Holy Spirit, three Persons, one Name, one Godhead. The Fathers drive the point hard: to name this Trinity is to name the one God; to drop any of the Three is to contradict Christ and empty the baptism. Hilary turns it against every error at once, against Sabellius who blurs the Persons into one, and against the Arians who make the Son a creature "out of nothing and in time." The whole of our salvation, he says, is contained in this one Triune Name.
Matthew 28:20 · KJVTeaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.
"Because what He had laid upon them was great, therefore to exalt their spirits He adds, 'I am with you always, even unto the end of the world'… And not with them only does He say that He will be, but with all who shall believe after them. For the Apostles were not to continue till the end of the world, but He says this to the faithful as to one body."
St. John Chrysostom"By ascending into heaven He does not desert His adopted; but from above strengthens to endurance, those whom He invites upwards to glory."
St. Leo the GreatFirst teach, then baptize, then teach them to obey, and the whole impossible task is carried by the last line: "I am with you always." Chrysostom notes the promise reaches past the Apostles to "the faithful as to one body", to us. And Leo adds the paradox of the Ascension: going up, He did not leave; He strengthens His people from above for the road to the same glory.
Where this stands among the traditions
This is ecumenical bedrock. Orthodox, Catholic, and Protestant alike baptize "in the name of the Father, and of the Son, and of the Holy Ghost," and read this verse, as the early church did, as a charter of the Trinity: one God in three Persons, the Son and the Spirit fully God with the Father. It is one of the texts on which the Nicene faith rests, and it stands against both the collapsing of the Persons (Sabellianism) and the demoting of the Son (Arianism). Not a point of division between the traditions, but one of their shared foundations.
Patristic text from the Catena Aurea (public domain, transcription lightly corrected). Scripture in the King James Version; the plain-language lines are our own restatement, not the Fathers' words. See also The Word Was God and Before Abraham Was, I AM; this passage in the Study Bible; and Matthew 28 at BibleHub.