From a Biblical perspective - if you're not for Him, or especially if you can/will corrupt His people (what was Israel, but now are all Christians) then you're basically worthless and God would rather you be destroyed than have you cause His children to sin and/or turn away from Him.
From Deuteronomy 20:
16 However, in the cities of the nations the LORD your God is giving you as an inheritance, do not leave alive anything that breathes. 17 Completely destroy them—the Hittites, Amorites, Canaanites, Perizzites, Hivites and Jebusites—as the LORD your God has commanded you. 18 Otherwise, they will teach you to follow all the detestable things they do in worshiping their gods, and you will sin against the LORD your God.
This goes completely counter to our culture though, which generally believes that each person's life is precious, special, and just as valuable as the next one. But I don't think this is really God's perspective.Now, a few caveats here. Please understand that this is not a reflection of my personal opinion toward non-Christians. I love and appreciate all of my friends, just as I periodically pray for all of them. Also, I know that God can and has used non-Christians/Israelites to accomplish His purposes. And I also know that some people become "His" (i.e. Christians) later in life than others, some even on their death bed.
I'm just saying that as a whole, God doesn't seem to have as high a sanctity of life as we humans tend to. What really counts for God is not how long you live, but whose side you're on while you're alive, and consequently where you go after you die.