Misused #1 – “We then, as workers together with Him also plead with you not to receive the grace of God in vain” (v 1). Anyone teaching irresistible grace or the inability to fall from grace has never read or does not understand verse 1.
Misused #2 – “Behold, now is the accepted time: behold, today is the day of salvation” (v 2). Ten times out of nine when I hear this verse quoted, it is in the closing portion of a sermon, used as an encouragement to respond to and obey the gospel without delay. This is not even close to how Paul is using Isaiah 49:8. Isaiah 49:1-13 is a discourse on the day of Christ, the Redeemer of Israel and a light to the Gentiles. Thus, Paul is using it in this same fashion to remind the Corinthians of the reality of salvation through Jesus Christ. These verses are more closely related to 2 Corinthians 5 than to the remainder of chapter 6.
Mistreated – Paul again visits the matter of his personal mistreatment as a minister of Christ, a subject to which he will return in chapter 11. I cannot help but think that theses repeated references to mistreatment are given as a contrast to the self-serving pseudo apostles who peddled the word of God for their own glory and benefit (cf 2:17; 10:12-18; 12:11-13). When a man is faithfully executing the work of an evangelist, Satan will use every tool at his disposal to discourage or discontinue that work. Through the ages, he has found mistreatment and persecution to be particularly effective in discouraging God’s people. We should expect and anticipate no less when we are doing God’s work.
Mismatched – “Do not be unequally yoked together with unbelievers” (vv 14-18). This passage does not forbid keeping company with unbelievers, for such would necessitate living on another planet (cf 1 Cor 5:9-10). Neither does it forbid doing business with unbelievers. Some would argue that the passage forbids the Christian from marrying an unbeliever, (a view I hold personally but not as a matter of faith), as the dangers and heartaches of such are manifest and manifold. The heart of the passage is forbidding the child of God from entering into relationships or partnerships where the unbeliever holds undue sway over the life and actions of the child of God. Our ONLY allegiance is to God! All other relationships or duties derive from and are guided by it. Do not put yourself if a position where you have to make a decision on whom you will serve!