NET

12 For our reason for confidence is this: the testimony of our conscience, that with pure motives and sincerity which are from God—not by human wisdom but by the grace of God—we conducted ourselves in the world, and all the more toward you.

Darby

Paul Explains His Change of Plans to Visit Corinth

12 For our boasting is this, the testimony of our conscience, that in simplicity and sincerity before God^D8379, (not in fleshly wisdom but in God's grace,) we have had our conversation in the world, and more abundantly towards you.

Darby Bible Notes

God - Lit. 'simplicity and sincerity of God.' The force I take to be, 'such as God would have, and God would produce.' As we say, 'That is the stroke of a master,' 'the act of a prince.' 'Godly' seems to me feeble, but not wrong. One cannot say 'of God' here.

KJV

Paul Explains His Change of Plans to Visit Corinth

12 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.

Strong's

12 For ^G1063 our^G2257 rejoicing^G2746 is^G2076 this^G3778, the testimony^G3142 of our^G2257 conscience^G4893, that^G3754 in^G1722 simplicity^G572 and^G2532 godly^G2316 sincerity^G1505, not^G3756 with^G1722 fleshly^G4559 wisdom^G4678, but^G235 by^G1722 the grace^G5485 of God^G2316, we have had our conversation^G390 in^G1722 the world^G2889, and^G1161 more abundantly^G4056 to^G4314 you-ward^G5209.