It would have to be one of the more spectacular conversions: in a moment, Saul believed the same Christ he had so violently opposed.
But it wasn’t that Saul didn’t worship God. When a voice from heaven asked him Why are you persecuting me?, his response (a question) showed that he knew God’s voice:
Acts 9:5 Who are you, lord?
And God’s reply showed that God knew Saul needed a little, but not much, explanation:
Acts 9:5-6 I am Jesus, the one you are persecuting! Now get up and go into the city, and you will be told what you must do.

Conversion of St Paul (La conversion de Saint Paul (vers 1690), Luca Giordano (1632–1705) )
Within days, Saul was preaching Jesus in the Damascus Synagogue, and he was so effective that the only recourse the leaders had there was to try to kill him.