There are three classes of people: Believers, the non believers, and the hypocrites. The following ayats 8-16 from Surah Baqarah are about the hypocrites.
8. Of the people there are some who say: “We believe in Allah and the Last Day” but they do not (really) believe.
9. Fain would they deceive Allah and those who believe but they only deceive themselves and realize (it) not!
10. In their hearts is a disease; and Allah has increased their disease and grievous is the penalty they (incur) because they are false (to themselves).
11. When it is said to them: “Make not mischief on the earth” they say: “Why we only want to make peace!”
12. Of a surety they are the ones who make mischief but they realize (it) not.
13. When it is said to them: “Believe as the others believe” they say: “Shall we believe as the fools believe?” nay of a surety they are the fools but they do not know.
14. When they meet those who believe they say: “We believe” but when they are alone with their evil ones they say: “We are really with you we (were) only jesting.”
15. Allah will throw back their mockery on them and give them rope in their trespasses; so they will wander like blind ones (to and fro).
16. These are they who have bartered guidance for error: but their traffic is profitless and they have lost true direction.
(Translation: Abdullah Yusuf Ali)