It seems that Paul forgot the third member of the Trinity, the Holy Spirit in his greetings at the beginning of his epistles.
Not entirely

Here are a few examples.
Eph 3:16-21
I pray that out of his glorious riches he may strengthen you with power through his
Spirit in your inner being,
17 so that
Christ may dwell in your hearts through faith. And I pray that you, being rooted and established in love,
18 may have power, together with all the saints, to grasp how wide and long and high and deep is the love of Christ,
19 and to know this love that surpasses knowledge — that you may be filled to the measure of all the fullness of
God.
20 Now to him who is able to do immeasurably more than all we ask or imagine, according to his power that is at work within us,
21 to him be glory in the church and in Christ Jesus throughout all generations, for ever and ever! Amen.
2 Cor 13:14
May the grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit be with you all.
1 Thess 5:19-28
Do not put out
the Spirit's fire;
20 do not treat prophecies with contempt.
21 Test everything. Hold on to the good.
22 Avoid every kind of evil.
23 May
God himself, the God of peace, sanctify you through and through. May your whole spirit, soul and body be kept blameless at the coming of
our Lord Jesus Christ.
24 The one who calls you is faithful and he will do it.
25 Brothers, pray for us.
26 Greet all the brothers with a holy kiss.
27 I charge you before the Lord to have this letter read to all the brothers.
28 The grace of our Lord Jesus Christ be with you.
Rev 22:17-21
The Spirit and the bride say, "Come!" And let him who hears say, "Come!" Whoever is thirsty, let him come; and whoever wishes, let him take the free gift of the water of life.
18 I warn everyone who hears the words of the prophecy of this book: If anyone adds anything to them
, God will add to him the plagues described in this book.
19 And if anyone takes words away from this book of prophecy, God will take away from him his share in the tree of life and in the holy city, which are described in this book.
20 He who testifies to these things says, "Yes, I am coming soon."
Amen. Come,
Lord Jesus.
21 The grace of the Lord Jesus be with
God's people. Amen.