"A fool finds no pleasure in understanding but delights in airing his own opinions."
I know I've blogged this before but I can't stress enough the importance of coming across with love and understanding. This world is going to constantly have people with beliefs contrary to the Word of God but we as Christians should not approach this with anger, strife and arrogance but with the understanding that they have not found the gift of Christ just as we all were lost once those people just simply need to be found. Prayer is the key to letting go whatever is putting a dividing line through you and that person. Prayer is very freeing because it puts whatever the problem is in the hands of the one you know can work it out. This also works with disagreements within the church. Maybe that person still has some growing to do in their walk with Christ, don't let that bother you or maybe it's you, maybe God is trying to get a message to you through that person. Pray about it and you will find out. Debating won't solve anything.
"Do everything without complaining or arguing, so that you may become blameless and pure, children of God without fault in a crooked and depraved generation, in which you shine like stars in the universe as you hold out the word of life -- in order that I may boast on the day of Christ that I did not run or labor for nothing." Philippians 2:14-16