Increased the more in strength - His conviction of the truth of the Christian religion became stronger every day, and hence his moral strength or boldness increased.
And confounded - See Acts 2:6. The word here means “confuted.” It means also occasionally “to produce a tumult or excitement,” Acts 19:32; Acts 21:31. Perhaps the idea of producing such a tumor is intended to be conveyed here. Paul confuted the Jews, and by so doing he was the occasion of their tumultuous proceedings, or he so enraged them as to lead to great agitation and excitement - a very common effect of close and conclusive argumentation.
Proving that this - This Jesus.
Is very Christ - Greek: that this is the Christ. The word “very” means here simply in the Greek: ὁ Χριστός ho Christos. It means that Paul showed by strong and satisfactory arguments that Jesus of Nazareth was the true Messiah. The arguments which he would use may be easily conceived, but the evangelist has not seen fit to record them.