1 Corinthians 1:18
For the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God.
2 Corinthians 2:15-17
15 For we are the aroma of Christ to God among those who are being saved and among those who are perishing, 16 to one a fragrance from death to death, to the other a fragrance from life to life. Who is sufficient for these things? 17 For we are not, like so many, peddlers of God's word, but as men of sincerity, as commissioned by God, in the sight of God we speak in Christ.
2 Corinthians 4:3
And even if our gospel is veiled, it is veiled to those who are perishing.
Matthew Henry's Concise Commentary
2:12-17 A believer's triumphs are all in Christ. To him be the praise and glory of all, while the success of the gospel is a good reason for a Christian's joy and rejoicing. In ancient triumphs, abundance of perfumes and sweet odours were used; so the name and salvation of Jesus, as ointment poured out, was a sweet savour diffused in every place. Unto some, the gospel is a savour of death unto death. They reject it to their ruin. Unto others, the gospel is a savour of life unto life: as it quickened them at first when they were dead in trespasses and sins, so it makes them more lively, and will end in eternal life. Observe the awful impressions this matter made upon the apostle, and should also make upon us. The work is great, and of ourselves we have no strength at all; all our sufficiency is of God. But what we do in religion, unless it is done in sincerity, as in the sight of God, is not of God, does not come from him, and will not reach to him. May we carefully watch ourselves in this matter; and seek the testimony of our consciences, under the teaching of the Holy Spirit, that as of sincerity, so speak we in Christ and of Christ.