This combination runs into all the usual problems with mixing martial and spellcasting classes, particularly with the berserker class. As is usual, you will want a mix of physical ability scores for combat and Wisdom for spellcasting. Having the berserker in the mix adds the additional challenge of not being able to cast spells while raging in most cases, and while the synergy feat chain ameliorates this in a limited manner, it is still a thing to keep in mind. Flavor-wise, this is a perhaps surprisingly easy combination to make work. Religious zeal that grants supernatural powers is a very common trope in fiction, particularly in darker settings, and as the concepts will illustrate, there are a few specific flavor pairings that almost feel made for each other. More levels of berserker will give you a pretty standard melee combat monster with a few spells to rely on for buffing and versatility. More levels in cleric gives you a combattrained priest with a bit of a temper (or perhaps a supernatural “overclock”). A roughly even mix is probably the best way to make the stereotypical “wild-eyed zealot” work. [[Synergy Feats for Multiclassers#Berserker w/ Cleric|Berserker-Cleric chains and ideas]]