That's real confusing. Christians and Jews kinda make sense.
But Communists?
Are you confused? I am confused. So there:
P.S. But I like the song, so I'll repeat it here:
"Allah, oh our Lord, vanquish Your enemies, enemies of the religionNow, all together!!!
[Islam] in all places.
Allah, strike the Jews and their sympathizers,
the Christians and their supporters,
the Communists and their adherents.
Allah, count them and kill them to the last one, and don't leave even one."
Er... a question, though: why should Allah, in his infinite wisdom, count them before killing them? Wouldn't it slow down the process? After all, being omnipotent, he knows exactly how many there are of these three kinds without counting... Or not?