Q. What makes Christianity different from other religions?

A. All other religions are some variant of the formula, "Obey, then God will accept you." 
Christianity says, "God accepts you, so that you can obey." 

Other religions say, "Try really hard to save yourself, and if you try hard enough, God will accept you." 
Christianity says, "God did all the work to save you.  You don't need to try at all, you just need to trust God."

Other religions say, "You need to earn your own salvation."
Christianity says, "You can't earn your salvation."

Other religions say, "Try really hard and you'll be able to appease God's wrath."
Christianity says, "You can't appease God's wrath, but God took care of it for you."

Christianity is completely God-centered.  God created us for a purpose - to enjoy and worship God.  We sinned against God.  God must punish sin.  God devised a way so that we could avoid being punished.  God lived the perfect life that we could never live.  God took the punishment that we deserved, by dying for our sin.  God saved us so that we could spend eternity with God.