I believe a began gathering these passages under these categories by looking first at Bavinck’s Reformed Dogmatics, but this has probably been supplemented from other sources as well over time. Scripture is quoted from the ESV.
There is only One God
Deuteronomy 6:4—“Hear, O Israel: The Lord our God, the Lord is one.
Isaiah 44:8—Fear not, nor be afraid; have I not told you from of old and declared it? And you are my witnesses! Is there a God besides me? There is no Rock; I know not any.”
Isaiah 45:21—Declare and present your case; let them take counsel together! Who told this long ago? Who declared it of old? Was it not I, the LORD? And there is no other god besides me, a righteous God and a Savior; there is none besides me.
John 17:3—And this is eternal life, that they know you the only true God, and Jesus Christ hom you have sent.
1 Corinthians 8:4—Therefore, as to the eating of food offered to idols, we know that “an idol has no real existence,” and that “there is no God but one.”
Ontological Unity of the Three Persons
John 10:30—30 I and the Father are one.” (see John 10:33, 38)
Matthew 28:19—19 Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit,
“And just as Jesus finally sums up his instruction in the name of the Father, of the Son, and of the Holy Spirit, so also the apostles again and again put these names side by side and on the same level.” [Bavinck, RD, 2:270.]
1 Corinthians 8:6—6 yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.
1 Corinthians 12:4–6—4 Now there are varieties of gifts, but the same Spirit; 5 and there are varieties of service, but the same Lord; 6 and there are varieties of activities, but it is the same God who empowers them all in everyone.
2 Corinthians 13:14—14 The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all.
2 Thessalonians 2:13–14—13 But we ought always to give thanks to God for you, brothers beloved by the Lord, because God chose you as the firstfruits to be saved, through sanctification by the Spirit and belief in the truth. 14 To this he called you through our gospel, so that you may obtain the glory of our Lord Jesus Christ.
Ephesians 4:4–6—4 There is one body and one Spirit—just as you were called to the one hope that belongs to your call— 5 one Lord, one faith, one baptism, 6 one God and Father of all, who is over all and through all and in all.
1 Peter 1:2—2 according to the foreknowledge of God the Father, in the sanctification of the Spirit, for obedience to Jesus Christ and for sprinkling with his blood: May grace and peace be multiplied to you.
1 John 5:4–6—4 For everyone who has been born of God overcomes the world. And this is the victory that has overcome the world—our faith. 5 Who is it that overcomes the world except the one who believes that Jesus is the Son of God? 6 This is he who came by water and blood—Jesus Christ; not by the water only but by the water and the blood. And the Spirit is the one who testifies, because the Spirit is the truth.
Revelation 1:4–6—4 John to the seven churches that are in Asia: Grace to you and peace from him who is and who was and who is to come, and from the seven spirits who are before his throne, 5 and from Jesus Christ the faithful witness, the firstborn of the dead, and the ruler of kings on earth. To him who loves us and has freed us from our sins by his blood 6 and made us a kingdom, priests to his God and Father, to him be glory and dominion forever and ever. Amen.
Unity of Purpose and Action Among the Persons of the Trinity
Luke 1:35—35 And the angel answered her, “The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy—the Son of God.
Matthew 3:16–17—16 And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him; 17 and behold, a voice from heaven said, “This is my beloved Son, with whom I am well pleased.” || Mark 1:10-11; Lk 3:21-22
John 5:26—26 For as the Father has life in himself, so he has granted the Son also to have life in himself.
1 Corinthians 12:4–6—4 Now there are varieties of gifts, but the same Spirit; 5 and there are varieties of service, but the same Lord; 6 and there are varieties of activities, but it is the same God who empowers them all in everyone.