"That changes everything"

Usually when I quote my students, it's because they said something funny. This time, one of them said something that has stuck with me for several days. I can usually tell when my students haven't practiced. When they have more interest in talking, and humming, and general wandering around the room before they sit down and get their books out, Ibegin to suspect that maybe they didn't practice. On Friday, I knew for sure that Alex hadn't practiced (because he misplaced his notebook and hadn't had it for over a week), but he was still humming, putting off playing, etc. I heard him singing under his breath "Joy to the world, the teacher's dead." He's not the type of kid that actually hates his teachers, but from what I can gather, his classmates had been singing it, and he picked it up, not really thinking about what he was singing. I asked him not to sing it, not because I was personally offended because I'm a teacher (my skin's a little thicker than that), but because of obvious problems with the song. He asked me why I didn't like it, and I said, "First of all, the words go against the Bible."
"They do?"
"Yes, in Exodus it says thou shalt not kill"
Then he made the statement "That changes everything, then!"
Does it really change everything for me? or do I continue to do what I want to do conveniently ignoring the Bible's commands against whatever it is?
I'm thankful that Alex has a tender heart, and that God used him to point out that what the Bible says really should change everything we say and do.