Infiniti2000 said:
Cheaper depends on the cleric and how much RP the wizard is willing to perform. Can you say, "Join me for services tomorrow at Dawn to worship the great Pelor and I'd happy to cast magic vestment on your buckler."
This could work both ways:
Fighter: "Are you willing to abandon your weak god and worship Tempus the Warlord henceforth? No? Then I cannot help you get out of the grapple with that orc barbarian, poor cleric"
Wizard: "Admit that the gods are false, and that arcane power triumphs over all, and I'm glad to cast fly on you so you won't drown in a minute when the water goes over your head."
Rogue: "Did you hear that 'click'? You've managed to hit a preassure plate, priest. I reckon that as soon as you take that foot away, the whole ceiling will come crashing down, robbing you of your third spatial dimension. But if you would be so kind as to sign this contract to help me steal all the artefacts from your church, I might give you some pointers about surviving this particular trap."
and so on
I'd rather say that these people are a team and will work together without one forcing the other to abandon their deities.
In our last campaign, there actually was a player whose priestess often demanded from others to change their faith in order to be healed - it was a pain in the lower back. She was a frickin' half-drow priestess of Eilistraee, not really appropriate for an elven bladesinger, for example.
On the other hand, that player cannot help but play power-hungry maniacs, no matter what he plays. Him playing cleric was a real bad move (he whined every time he was asked to heal someone because it took away his precious spells and demanded we get healing potions)