Why Would Anyone Consider Islam a Race?

Islam is obviously not a race, but a religion.  If you hesitate to call Islam a religion, then it is either a political ideology masquerading as a religion, or a hybrid ideology that blends features of religion and political ideology, or a Christian heresy.  On any of these interpretations it is not a race.  That should be perfectly clear.

No race has apostates. Islam has apostates. Ergo, etc.

With respect to religions and political ideologies, there are conversions and de-conversions. One cannot convert to, or de-convert from, one's race. Ergo, etc.

Why then do some want to call Islam a race?  Here is a very plausible answer. I know of no better:

Criticizing Islam is not racism.  There is no such thing as "anti-Muslim racism" any more than there is "anti-Christian racism," "anti-Republican racism," or "anti-Capitalist racism." 

So why would anyone claim differently?

It is because the battle over Islam is being fought in the West, the only arena in which it can still be critically debated.  It is also here that repugnance toward racism is strong and nearly universal.  From politics to high-risk mortgages and illegal immigration, fear of the race card is one of the strongest influences on public policy.

At the same time, it is nearly impossible to defend Islam on its own merits in the West in free and open debate.  According to its own texts, the religion was founded in terror.  Its political and social code is deeply incompatible with liberal values.

Muslims societies usually rely on threat of violence to suppress intellectual critique of Islam and the freedom of other religion to fairly compete, which, if allowed, would be the slow death of Islam.  Their counterparts in the West have learned to rely on the race card.  If they can paint any criticism of their religion as "racism," then the massive evidence against Islam can be dismissed out of hand without having to contend with it.

Slinging the worst of all slurs to compensate for deficiency of fact and logic is weak enough, but it is ironic given that what is being defended in such cheap fashion is an ideology that is overtly supremacist in nature. 

That's right. Islam is supremacist in nature. Not racially supremacist, but ideologically supremacist. Leftists try to hide this fact by calling critics of Islam racists, from which they then slide to the vicious slur that these critics are white supremacists, which brings them back to the 'race card,' the only card in their deck and the one they never leave home without.