So I strive always to keep my conscience clear before God and man. Acts 24:16
Paul was a principled man guided by a strong conscience. His entire life displays a devotion to doing what he thought was in accordance with God's will, his conduct reflecting that sincerity. His actions as a Pharisee were governed by many of the same biblical principles extant after his conversion. In a sense, he became a Christian because God persuaded his conscience that it was the right thing for him to do. In other words, when God converted him, He did not change Paul's conscience but his perception of what was right—of what God's will actually was.

The Bible reveals Paul, prior to his conversion, as one who was sincerely wrong. His actions did not reflect the actual will of God, but instead, those of a man determined to do what he sincerely believed was “wise in his own eyes” (Isaiah 5:21). In Acts 26:9, Paul admits, “Indeed, I myself thought I must do many things contrary to the name of Jesus of Nazareth.”

We should be wary of such misguided sincerity. Yet, if we strive, like Paul, to avoid hypocrisy and follow our conscience in all matters, God's judgment will take our motivations into account (Proverbs 21:2; Romans 14:22-23; I Timothy 1:13).