Matthew 26:42
He went away a second time and prayed, “My Father, if it is not possible for this cup to be taken away unless I drink it, may your will be done.”
If Father and Son and Holy Spirit are the same divine person, while Jesus prayed the Father, prayed himself?
Father and Son and Holy Spirit are not the same divine person, but are three divine persons distinct from each other by their original relations, which, however, fully participate in the same and indivisible divine substance, and therefore are one God: The Father is God (John 1:18; Romans 15:6), the Son is God (John 20:28; Titus 2:13; 2 Peter 1:1), the Holy Spirit is God (Acts 5:3-4; 1 Corinthians 3:16). But they are not three gods, since – as has already been said – they fully participate in the same and indivisible divine substance, and therefore they are one God. Jesus as the Son is not the Father, but is a person distinct from the Father, and therefore did not pray to himself.
If the three divine persons are one God, and therefore participate fully in the same and indivisible will – as well as in the same and indivisible substance or nature – because Jesus says he wants to do the will of the Father, as we read in Matthew 26:42: “Father, may your will be done” ?
When the fullness of time came, the Son of God hypostatically united to himself a flesh animated by a rational soul (John 1:14; Galatians 4:4), making himself similar to us in everything except sin (Hebrews 4:15). Therefore in Jesus Christ there are two natures, divine and human, without confusion or change or division or separation. Both natures, divine and human, retain their integrity. In Jesus Christ, just as there are two natures, so there are two natural wills, the divine (common to all persons of the Trinity) and the human, indivisible, immutable, not confused. The human will is subjected, without opposition or reluctance, to the divine and omnipotent will, according to the words of the Third Council of Constantinople. Therefore, the words of Jesus: “Father, not as I will, but as you will” (Matthew 26:39), and: “May your will be done” (Matthew 26:42), must be referred to his human will, subjected without opposition or reluctance to the divine will. Similarly in Hebrews 10:7: Then I said, ‘Here I am—it is written about me in the scroll—I have come to do your will, my God.’ Words that must be referred to the human will of Jesus Christ, who wants to fulfill the divine will. And so in John 5:19: “The Son can do nothing by himself; he can do only what he sees his Father doing, because whatever the Father does the Son also does.” These words too must refer to the human will of Jesus, subjected to the divine will.