KJV:
For our rejoicing is this, the testimony of our conscience, that in simplicity and godly sincerity, not with fleshly wisdom, but by the grace of God, we have had our conversation in the world, and more abundantly to you-ward.
NASB:
For our proud confidence is this: the testimony of our conscience, that in holiness and godly sincerity, not in fleshly wisdom but in the grace of God, we have conducted ourselves in the world, and especially toward you.