How come christians...?

As a christian, I mainly answer questions in the religion and spirituality section here on Yahoo! and I see a lot of christians answer questions and they are extremely rude sometimes. God says that you should witness and explain and answer with kindness and respect, so why do you act so rude to non-christians sometimes? If I were the non-christian and a christian person answered my questions rudely, I wouldn't want to come to God. I would think that all christians were rude and that I wouldn't want to become that. So please be more kind when answering for God's sake, so that way maybe more people will come to know him.