I took the opportunity last Friday to wish all my non-Catholic co-workers a "blessed Feast of the Immaculate Conception". I was truly surprised with the variety of responses I received, from an amused chuckle to, "I don't even want to know what that is. It sounds like some sort of bizarre sexual thing."
To this, from one of my non-denominational co-workers, I answered, "No, it's just our celebration of Mary's having been born without original sin."
"Oh, I don't believe in that original sin nonsense," he answered. "That's just a big guilt trip."
"Hmm. I'm not sure you understand what original sin is," I answered. "What do you think Catholics mean by that?"
"Why don't you tell me what it means and I'll tell you what I think about it," he answered. I explained to him that, because our original parents fell from grace, we are subject to suffering and death and will undoubtedly lead lives dotted with sin, and that salvation means being brought back into a right relationship with God. "Well, I can buy that," he answered.
See, sometimes it just takes a clear explanation.
Another co-worker, a member of an instrumental Church of Christ, asked me, "Now this is the thing about Mary, right?"
"Yes," I answered. "It means that Mary was conceived without original sin."
"Mary was too born with original sin," she objected.
"So you believe in original sin?"
"Well, no, I don't believe in that, either," she said.
"So ... if you don't believe original sin exists, how could Mary have been born with it?"
"I'll have to think about that," she said.
Of course, my presentation of the faith in this last dialog is completely silly, it was a fun Catch-22.