"Do you not know that a little yeast leavens the whole batch of dough?" says St. Paul to the Corinthians. Sometimes "just a little" does hurt. Having one area of our lives that isn't dedicated to God, having a "secret sin" or one thing that we keep all for ourselves, can really be to our detriment. We hear all the time that a little won't hurt, or it won't hurt just to look, or I'm just looking, not touching! But what does looking hurt? It hurts our own spirit. When we are looking at something, be it another woman or man other than our spouse, be it a nicer car, a bigger house we could never afford, be it violence on television, it hurts our spirit.
It has been proven that watching violence on television desensitizes people to violence. We don't even flinch or are even appalled by someone being shot and killed. This is so true that violent television shows and movies are moving to more and more graphic details on how one is killed and even show killings that are not shootings but torture. And yet we watch. Crime television seems to be more popular than anything else on TV - how many Law and Orders and CSIs do we need to have? The same must be true of seeing other things on television, sex, nudity, etc. We must also become desensitized to that and then translate what we see there to our spouse - forgetting that what we saw on television is not real.
If we really want to be wholly dedicated to God, we have to be careful about what we watch and what kinds of activities in which we participate. As St. Paul says in his letter to the Phillipians (4:8) "Finally, brothers, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable--if anything is excellent or praiseworthy--think about such things."