Why is God a Trinity?

      In the Name of the Father, and of the Son, and of the Holy Spirit. Amen! Trinity. Day of the Holy Spirit. Holy Apostles: Andrew, John, Matthew, Mark, Luke, Paul; holy hierarchs: Basil, Gregory, John, and Nicholas; venerable ones: Simeon the New Theologian, Gregory of Sinai, Gregory Palamas, Maximus the Confessor; venerable ones: Macarius, Anthony, Athanasius; venerable ones: Sergius, Seraphim, Nilus, Silouan, and all saints, pray to God for us! [John 7:16-18] Jesus answered them, saying: My teaching is not Mine, but His who sent Me; if anyone wants to do His will, he will know concerning the teaching, whether it is from God or whether I speak on My own authority. He who speaks on his own authority seeks his own glory; but He who seeks the glory of Him who sent Him is true, and there is no unrighteousness in Him. [John 15:26-27] But when the Helper comes, whom I shall send to you from the Father, the Spirit of truth who proceeds from the Father, He will bear witness of Me; and you also will bear witness, because you have been with Me from the beginning. [John 16:3-14] And they will do these things because they have not known the Father nor Me. But I have said these things to you, that when the time comes, you may remember that I told you of them; and I did not say these things to you at the beginning, because I was with you. But now I go away to Him who sent Me, and none of you asks Me, ‘Where are You going?’ But because I have said these things to you, sorrow has filled your heart. Nevertheless, I tell you the truth: it is to your advantage that I go away; for if I do not go away, the Helper will not come to you; but if I depart, I will send Him to you. And when He has come, He will convict the world of sin, and of righteousness, and of judgment: of sin, because they do not believe in Me; of righteousness, because I go to My Father and you see Me no more; of judgment, because the ruler of this world is judged. I still have many things to say to you, but you cannot bear them now. However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come. He will glorify Me, for He will take of what is Mine and declare it to you. [Acts 2:1-4] When the Day of Pentecost had fully come, they were all with one accord in one place. And suddenly there came a sound from heaven, as of a rushing mighty wind, and it filled the whole house where they were sitting. Then there appeared to them divided tongues, as of fire, and one sat upon each of them