Though the castle is consecrated and the reliquary taken to heaven along with the cult, there still might be something useful left. "Red Killer, scour the remnants of the castle. Find what you can."
She gleefully skips into the blood-soaked castle ruins, leaving the whimpering boy by your side. Red Killer comes back out in a matter of minutes, exclaiming that she found the church's tributes; a small fortune of cash. The undead have no need for money, of course, but the living do. However, you don't have a means to haul your loot, not unless your zombie pack-mules collapse mid-journey. You need more durable servants.
You order what little zombies you have to gather the corpses to where you are. There seems to be much more bodies usable for reanimating than you expected! Though Red might not make a good necromancer, she can still help you prepare the bodies. She 'coerces' the boy to help as well, once you've taught her how to mark the body and drain the blood.
Naturally, the two children mess up some of the corpses. However, many of them are done well, and reanimation goes smoothly. The dead you raise do not shuffle anymore, nor do they moan or groan. Of course, they're far from your best work, but these are much better than the makeshift army you had.
You realize it's been almost an entire day. Such is the preparation and dedication to raise truly formidable undead. Red Killer is soundly asleep in a blood-spattered house on a bed caked with dried blood, the boy laying frightful and awake beside her. You sealed his wounds earlier, ensuring that he wouldn't die prematurely. It's night again...
You hunger for another soul. Raising from the ground once more, enveloped by ancient spirits, you begin another ritual. However, you cannot find a suitable soul worth all the time and trouble. You could try anyway, with a sub-par soul.