Why do you interpret "living for something" to mean "living for god"? Anberlin may be a christian band, but many non-christians listen to their music and find different meanings than living for god.
It sounds to me that he's singing about a hard time in his life and he has to do more than be alive to get through it and achieve happiness, he has to work hard for the ones he loves. And he is using his one life to care for and protect his loved ones.