Devils advocate?

So I had this intense discussion with a friend today...he was saying that it is okay to stand up for what he does not believe in just to play the devil's advocate. That perhaps you may have a better understanding of how someone else might be feeling if you are on the "opposite side" than they are...or atleast that is what I heard him saying. I just was put back by it because to me it is playing with fire. I don't want to nor will I ever stand up for "sin" or something I don't take a stand on just for the sake of debate and discussion. It does not matter who it is with...I still think that we have to be so careful. It scared me and I actually became really confused. No I don't think that it is wrong per say..I guess I keep hearing this annoying, but very true phrase my mom used to say (and now my dad uses), "Why do we walk so close to the line, are we just seeing how close we can get without going over it?"...I know that we need to be accepting and loving and etc. with others that are pre-Christians but, I will not and choose not to advocate for sin...I am trying hard enough to get rid of the sin in my own life nevertheless advocating for some controversial subject that I might disagree with just for the sake of discussion. I think Satan wants to use situations like that to make it sound okay with us, and to see how sin might be like for others etc. Anyhow I don't know if I am making any sense...I just am still going over all of this in my head. I am trying to be understanding. I cautioned my pal that he should be really careful when getting into these debates. I was part of one last night and there was a very moldable teen who really admires my friend listening to him play the "devils advocate"...I just think that we need to be cautious...anyhow I am running late for a dinner date and need to go. Help me understand Lord, and I pray that I just am who you want...not for anyone else's sake but for you Lord. Any"who"...Take all this for whatever it's worth...It is just SDV (sara dilbone version). See ya