Dis. J.W You make an excellent point, and one which just shows I should have read the O.P with the care and attention you did !
Stephen/Chalam is wrong to claim that Paul asserts anywhere in his genuine writings, that Jesus is God in a trinitarian sense.
Paul's view of Jesus is that he was pre-existent in heaven, and that God (the father) raised him from the dead. Quite where Paul stood on the extent of the Divinity of J.C. is not clear, but certainly there is not one hint in his writings of even a nascent trinitarian view, as far as I can see.
What was plain was that the Gospel he preached was that if you became "one in Christ" not only Sin from Adam was cancelled, but the power of Sin in your life now. This message obviously appealed, hence the fast spreading flame of Christian belief after Paul's ministry.