Paul did not believe or teach that his God was Jesus Christ. He was Jew just like all first Christians were.
This is what Paul believed and taught:
Romans 3:29 Or is he the God of the Jews only? Is he not also the God of people of the nations? Yes, also of people of the nations. 30 Since God is one, he will declare circumcised people righteous as a result of faith and uncircumcised people righteous by means of their faith.
... 15:5 Now may the God who supplies endurance and comfort grant you to have among yourselves the same mental attitude that Christ Jesus had, 6 so that unitedly you may with one voice glorify the God and Father of our Lord Jesus Christ.
1 Corinthians 8:5 For even though there are so-called gods, whether in heaven or on earth, just as there are many “gods” and many “lords,” 6 there is actually to us one God, the Father, from whom all things are and we for him; and there is one Lord, Jesus Christ, through whom all things are and we through him.
... 15:24 Next, the end, when he hands over the Kingdom to his God and Father, when he has brought to nothing all government and all authority and power. 25 For he must rule as king until God has put all enemies under his feet. 26 And the last enemy, death, is to be brought to nothing. 27 For God “subjected all things under his feet.” But when he says that ‘all things have been subjected,’ it is evident that this does not include the One who subjected all things to him. 28 But when all things will have been subjected to him, then the Son himself will also subject himself to the One who subjected all things to him, that God may be all things to everyone.
2 Corinthians 1:3 Praised be the God and Father of our Lord Jesus Christ, the Father of tender mercies and the God of all comfort, 4 who comforts us in all our trials so that we may be able to comfort others in any sort of trial with the comfort that we receive from God.
... 11:31 The God and Father of the Lord Jesus, the One who is to be praised forever, knows I am not lying.
Galatians 1:1 Paul, an apostle, neither from men nor through a man, but through Jesus Christ and God the Father, who raised him up from the dead (...) 3 May you have undeserved kindness and peace from God our Father and the Lord Jesus Christ. 4 He gave himself for our sins so that he might rescue us from the present wicked system of things according to the will of our God and Father, 5 to whom be the glory forever and ever. Amen.
Ephesians 1:3 Praised be the God and Father of our Lord Jesus Christ, for he has blessed us with every spiritual blessing in the heavenly places in union with Christ, 4 as he chose us to be in union with him before the founding of the world, that we should be holy and unblemished before him in love. 5 For he foreordained us to be adopted as his own sons through Jesus Christ, according to his good pleasure and will, 6 in praise of his glorious undeserved kindness that he kindly bestowed on us by means of his beloved one. 7 By means of him we have the release by ransom through the blood of that one, yes, the forgiveness of our trespasses, according to the riches of his undeserved kindness.
... 4:4 One body there is, and one spirit, just as you were called to the one hope of your calling; 5 one Lord, one faith, one baptism; 6 one God and Father of all, who is over all and through all and in all.
... 5:20 always giving thanks to our God and Father for everything in the name of our Lord Jesus Christ.
... 6:23 May the brothers have peace and love with faith from God the Father and the Lord Jesus Christ.
Philippians 2:11 and every tongue should openly acknowledge that Jesus Christ is Lord to the glory of God the Father.
... 4:19 In turn my God will fully supply all your need according to his riches in glory by means of Christ Jesus. 20 Now to our God and Father be the glory forever and ever. Amen.
Colossians 1:3 We always thank God, the Father of our Lord Jesus Christ, when we pray for you,
... 3:17 Whatever it is that you do in word or in deed, do everything in the name of the Lord Jesus, thanking God the Father through him.
1 Thessalonians 1:1 Paul, Sil·vaʹnus, and Timothy, to the congregation of the Thes·sa·loʹni·ans in union with God the Father and the Lord Jesus Christ: May you have undeserved kindness and peace. 2 We always thank God when we mention all of you in our prayers, 3 for we continually remember your faithful work, your loving labor, and your endurance because of your hope in our Lord Jesus Christ in the presence of our God and Father.
... 3:11 Now may our God and Father himself and our Lord Jesus make a way for us to come to you. 12 Moreover, may the Lord cause you to increase, yes, to abound in love for one another and for all, just as we do for you, 13 so that he may make your hearts firm, blameless in holiness before our God and Father at the presence of our Lord Jesus with all his holy ones.
A true Christian seeks and clings to the truth; he does not fool himself with vain reasoning. Did Paul believe that Jesus Christ was his God?