Here's Ali Eteraz setting out a manifesto for the 'Muslim left' (follow the links to his earlier CiF articles on the need for reform within Islam, and take a look at his blog). Eteraz's call for a 'Muslim secularism' may seem like a contradiction in terms to those who wilfully misunderstand the meaning of secularism - interpreting it as an attack on religion per se, rather than simply a belief in the separation of church/mosque and state. Seen in this light, 'Christian secularism' is not an impossibility either: indeed, as I've suggested before, Arab Christians have often been the most ardent supporters of secularism, viewing it as their best protection as a religious minority in majority-Muslim countries.
Of course, those of us on the secular left who are neither Muslims or Christians would prefer it if our fellow-leftists in the majority-Muslim world didn't feel the need to prefix their political identity with a religious label. But Muslim and Christian progressives who are committed to secularist principles should be welcomed as allies in the fight to defend liberal values.