Matthew 16:24-28 (NLT) Then Jesus said to his disciples, “If any of you wants to be my follower, you must give up your own way, take up your cross and follow me.  If you try to hang on to your life, you will lose it. But if you give up your life for my sake, you will save it. And what do you benefit if you gain the whole world but lose your own soul? Is anything worth more than your soul? For the Son of Man will come with his angels in the glory of his Father and will judge all people according to their deeds. And I tell you the truth, some standing here right now will not die before they see the Son of Man coming in his Kingdom.”
When our motivation for service is to be a good person by serving others in our own strength, we can easily drift into religion. True service is when we let God serve through us, putting the emphasis more on Christ and less on us. This is the path of faith, where we think about God (not ourselves) building us up, where we think about God serving the world through us.