"Oh be Careful Little Eyes"

When I was growing up we sang a song in Sunday School, the final verse went something like this,

"Oh be careful little eyes....ears.....mouth....what you do,
Oh be careful little eyes....ears...mouth...what you do,
for the father up above is looking down in love,
oh be careful little eyes....ears...mouth what you do."

A very catching little song, but the words mean so much more now that I am a parent.  A friend and I were having a discussion the other day about how old children should be to watch a movie that involved language.  I pondered the question for only a moment when this song started playing in my head.
 My response was I want my children to always be sensitive to the sin of this world.  Our hope and prayer is that they are to be in this world, not of it. There is no way to protect them 24/7 from language, sex and the like but I am not going to make the conscious choice to allow them around it.  This person responded that they might be old enough to one day block out language.  I am almost 33 and language still makes me squirm when I am around it, whether it is in a move or another person is saying it.  I am sensitive to the sin, and I am very aware of it, especially if I falter and use a word.  That is the worst.
Sin should not be something we "block out" or "get used to."  If that is the case then our spirits are numb to what is actually going on.  I love my children with every fiber of my being.  We do no live in a perfect world and they need to understand that.  We are made perfect by God's love and forgiveness but we are not to join in on a movie, conversation or song just because we can block the sin out.  We are called to honor the Lord in word and deed, our bodies are His temple and we should do everything in our fiber to do His will.
I could never give my friend a straight answer, just what I said above and I pray that the Lord can guide the rest.