Many Muslims think of Christians as infidels, but both are sinners and require repentance.
Jesus said, “Suppose ye that these Galileans were sinners above all the Galileans, because they suffered such things? I tell ye, Nay; but, except ye repent, ye shall all likewise perish. Or upon those eighteen, upon whom the tower in Saloam fell, and slew them, think ye that they were sinners above all men that dwelt in Jerusalem? I tell you, Nay: but, except ye repent, ye shall all likewise perish.” (Luke 13:2-5)