It's the old "enemy of my enemy" thinking. Liberals really believe that Christians are their enemies and are actively working to make this country some kind of fascist theocracy. Being absolutely blind to the fact that Muslims actually have quite a few countries that are currently fascist theocracies, they only see that Muslims and Christians disagree on many things, so naturally embrace them as allies.
That's why we call them DUmmies...
PREMISES
1. Christians are benighted and unreasonable
2. Christians hold sway over the most advanced nations of the world
3. Christians have done so through conquest and imperialism
4. All lesser societies are victims
5. Lesser societies are therefore blameless for their plights
And they believe Muslims will be more manageable. After all, those evil European colonials oppressed the Muslims and stole their oil so as soon as the liberals overthrow the old order the Muslims will embrace the liberals as the savior of the brown man.
It reeks of self-congratulating paternalism.