I followed a little bit of this and I'm not an expert here at all but if one loves the Lord, with all his/her heart, how could one not serve him? Those who are in the body of Christ and are actively working with God in their faith want to serve, and they do. So if you're just sitting around when your neighbor needs a hand, or if you're living a wanton lifestyle of greed and power while others are suffering and you proclaim Christ - well, you never knew him.
My issue has been one cannot be saved without ever doing any works at all, and you example confirms that.
You posted "...but if one loves the Lord, with all his/her heart, how could one not serve him? Those who are in the body of Christ and are actively working with God in their faith want to serve, and they do." and this is NOT "faith only" but is loving obedience that earns you NOTHING.