2 Corinthians 11:13-15
2Co 11:13 Because these false missionaries, deceitful workers, are disguising themselves as missionaries from Christ.
2Co 11:14 And that does not surprize me, because even Satan disguises himself as an angel of light.
2Co 11:15 So it is no surprise when his servants, also, disguise themselves as servants of righteousness. Their destiny will match their works.
Paul and his team of true missionaries brought the gospel to Corinth, and some time later some false missionaries showed up. They pretended to be doing the same thing Paul did, but in reality their goal was the opposite. They wanted to undermine the true gospel, and lead people away from Christ. They opposed Paul and his influence. Paul is pointing this out to the Corinthians.
LORD, keep us focused on your gospel, and the works that accompany it. Make us aware when it is being undermined.