Why did Christ say "the Father sent me"?

[Baotloi]

We believe in the Trinity and that God is 3 in 1. Why did Jesus say or mentioned the Father as a second or separate person? Why couldn’t he just say “I came from heaven” instead of “the Father sent me”? Or when he tells the Apostles he will sent the Holy Spirit, why couldn’t he say “I, myself, will still be with you to guide you.” I don’t deny the Trinity at all. This was a question raised by a Protestant friend.

 

[Fr.Charles_Grondin]

Because they are separate persons. Father, Son, and Holy Spirit are three separate and distinct persons who share one divine nature.

Baltimore Catechism:

32. How are the three divine Persons, though really distinct from one another, one and the same God?

The three divine Persons, though really distinct from one another, are one and the same God because all have one and the same divine nature.

(a) Because the three divine Persons have one and the same divine nature, they have the same perfections and the same external works are produced by them. But in order that we may better know the three divine Persons, certain perfections and works are attributed to each Person; for example, omnipotence and the works of omnipotence, such as creation, to the Father; wisdom and the works of wisdom, such as enlightenment, to the Son, love and the works of love, such as sanctification, to the Holy Ghost.

Catechism of the Catholic Church:

**254 **The divine persons are really distinct from one another. “God is one but not solitary.” “Father”, “Son”, “Holy Spirit” are not simply names designating modalities of the divine being, for they are really distinct from one another: “He is not the Father who is the Son, nor is the Son he who is the Father, nor is the Holy Spirit he who is the Father or the Son.” They are distinct from one another in their relations of origin: “It is the Father who generates, the Son who is begotten, and the Holy Spirit who proceeds.” The divine Unity is Triune.

**255 **The divine persons are relative to one another. Because it does not divide the divine unity, the real distinction of the persons from one another resides solely in the relationships which relate them to one another: “In the relational names of the persons the Father is related to the Son, the Son to the Father, and the Holy Spirit to both. While they are called three persons in view of their relations, we believe in one nature or substance.” Indeed “everything (in them) is one where there is no opposition of relationship.” “Because of that unity the Father is wholly in the Son and wholly in the Holy Spirit; the Son is wholly in the Father and wholly in the Holy Spirit; the Holy Spirit is wholly in the Father and wholly in the Son.”