2 Corinthians 11:14-15 KJV And no marvel; for Satan himself is transformed into an angel of light. 15 Therefore it is no great thing if his ministers also be transformed as the ministers of righteousness; whose end shall be according to their works.
Yes, I would say they are in a lot of Churches, even leading them.
2 Peter 2:1-2 KJV But there were false prophets also among the people, even as there shall be false teachers among you, who privily shall bring in damnable heresies, even denying the Lord that bought them, and bring upon themselves swift destruction. 2And many shall follow their pernicious ways; by reason of whom the way of truth shall be evil spoken of.