II Corinthians 11:12-15

But what I do, I will also continue to do, that I may cut off the opportunity from those who desire an opportunity to be regarded just as we are in the things of which they boast. For such are false apostles, deceitful workers, transforming themselves into apostles of Christ. And no wonder! For Satan himself transforms himself into an angel of light. Therefore it is no great thing if his ministers also transform themselves into ministers of righteousness, whose end will be according to their works.