You can't convince people steeped in denial. The Trinity doesn't need to be defended, the evidence for it is the entire testimony of Christ in the Bible collectively. Anti-Trinitarians simply choose verses and passages to feed their denial.
There's not one single verse in the OP referencing Isaiah or Revelation either, because the more you broaden the message, the more the Trinity comes into view without even needing to scrutinize the texts.
I said
The only three in one trinity in the whole bible is serpent, devil, satan.
Rev 12:9
9 So the great dragon was cast out, that serpent of old, called the Devil and Satan, who deceives the whole world; he was cast to the earth, and his angels were cast out with him.
(NKJ)
The biggest problem with the trinity is it mocks Jesus and God. To believe in the trinity doctrine one must believe that Jesus lied, and Paul lied. Jesus said the Father is the only true God. Paul said for us true believers there is only one God the Father.
John 17:1-3
1 Jesus spoke these words, lifted up His eyes to heaven, and said: "Father, the hour has come. Glorify Your Son, that Your Son also may glorify You,
2 "as You have given Him authority over all flesh, that He should give eternal life to as many as You have given Him.
3 "And this is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent.
(NKJ)
1 Cor 8:6
6 yet for us there is one God, the Father, of whom are all things, and we for Him; and one Lord Jesus Christ, through whom are all things, and through whom we live.
(NKJ)
John 20:17
17 Jesus said to her, "Do not cling to Me, for I have not yet ascended to My Father; but go to My brethren and say to them, 'I am ascending to My Father and your Father, and to My God and your God.'"
(NKJ)