Many cite lines from his Essay on Man as speaking to Islam and other religions. You can find the entire essay online at https://www.gutenberg.org/files/2428/2428-h/2428-h.htm
The following lines appear to be critical:
For modes of faith let graceless zealots fight; His can’t be wrong whose life is in the right: In faith and hope the world will disagree, But all mankind’s concern is charity: