MTG Salvation

I'm disappointed, but I thank you for your input. It doesn't exactly kill my deck knowing this. As most of my creatures trigger something when they die. Would be nice to use those sac's towards a cost though, oh well, now I know. Thank you.

So, I recently built a Sac deck, and me and a buddy have had a few quarrels about how sacrificing works. My question is, if I use a card such as Fleshbag Marauder which makes both of us sacrifice a creature, can I use it as a cost for something like Vampiric Rites, or Jinxed Idol, since activated abilities can be activated at any time unless otherwise stated? Can I use the creature I was just required to Sac be used for those costs or no? I understand I need to Sac an additional creature for each cost, I'm just wondering if a card makes me sacrifice a creature as it resolves, not as a cost, can I use it towards a cost of an activated ability or instant? My friend seems to think I can't, but I think I should be able to. Can anyone help me out here?