All Roads Lead to Rome?

When the topic of religion is brought up with nonbelievers (or "unbelievers"... whichever they're called), probably the most frequent things we'll hear people say are, "all religions are basically the same," "They all lead to heaven," "They all believe in a God," etc. The phrase "all roads lead to Rome" basically comes from ancient Rome where, yes, all roads from all countries eventually did lead to Rome. It was their final destination. So my question is, how would you respond? Are all religions basically the same?

One thing I used to say was, "Well suppose you had a final exam and there was only one question, 'Which religion is right?', wouldn't you want to have the right answer? I mean, a lot might be at stake." Then someone pointed out to me that this would make it seem that God was being a bit petty... like "you didn't choose MY religion," or "*beep*! Wrong title!" So yeah, it's not about the title... it's about a LOT more. But how do you explain the differences in a succinct (short and sweet) way? How do you explain what is really at stake? Suppose you only have like 3 minutes before their attention switches to another topic?

They assert "all religions are the same - pick your poison, basically" and you assert "no they're not". One assertion against another. Now you gotta get to get to the nitty gritty of it with very little time.