Ye have heard. — Rather, ye heard. It was indeed notorious; but the Apostle may be referring to the fact that he himself usually (see Acts 22:3-21; Acts 26:4-20; 1 Corinthians 15:8-10) brought his own career and experiences into his preaching, so that they may have heard it from his own lips.
My conversation... in the Jews’ religion. — How I behaved in the days of my Judaism. The phrase “Jews’ religion” (literally, Judaism) is not used with any sense of disparagement.
Wasted it. — The same word is translated “destroyed” in Acts 9:21 : “Is not this he that destroyed them which called on this name?”