He was offended when I reminded him that I had asked him not to send me anything with profanity in it. He accused me of sticking my head in the sand and questioned my Christianity.
When a discussion (Debate) turns into a personal attack, the attacker has just lost the debate.
Jon-Marc, you had asked your friend not to send you offensive material and he did anyway. When you called him on that fact he responded by attacking your reason for keeping that sort of thing out of your life. Then he tried to justify his own actions with the old "Everybody does it" 8 year old mentality argument.
I suppose you could have replied with;..."If all of your friends jumped off of a bridge..."
But that probably wouldn't do any good.
If he were my friend, I might remind him of the importance of words. All the universe was created with the Word. Jesus raised the dead with the Word. Christians are representatives of Jesus Christ and the words we use and share should glorify and give praise to God.
Calling someones mother, who is a child of God, and created in His image, calling her a female dog, does not glorify His creation and has no place in the mouth of a Christian.
I wish more people, like you, would just put "Jesus Christ" in the "CC" box of their e-mail before they hit send.