UnquietDad, that's because those who aren't rabidly religious tend to keep such matters private in real life.
Anyway, I am one of those people who waited (and yes, it was for religious reasons). So did the DW. Just to note that what slhilly said earlier accords with my own teenage memories (including those of my siblings). Much as I'd like to think that I didn't get any sexual experience that early because of the strength of my convictions and morals, I suspect really it was because I just wasn't particularly attractive.
My only sexual experience prior to marriage was a relationship which involved an awful lot of muff-diving; an experience for which I am grateful (and I hope and trust the girlfriend in question was grateful too - she certainly wanted a lot of it).
I got married at 25 and lost my virginity on my wedding night. It was a rather unmemorable experience. I have been very happily married for close to ten years now, and my marriage is very strong. We are, for the most part, very happy with each other and very committed to our relationship and our children. I have to admit though that sex is perhaps not a strength of the relationship, and I wouldn't be surprised if it dried up in the next fifteen years or so. My DW likes sex, and we have it regularly enough, but tends to be a bit down on our list of priorities.
Some of you may think that what I have written sounds dire. I do admit that it would be nice to have a sexual relationship with someone with whom I 'click' with in bed, as I do with my wife in all other respects. The truth is, however, that what I looked forward to, even when I was a hot and hormonal teenager, was a committed relationship with a woman: if you had asked me back then whether I would prefer hot sex in an unstable relationship, or average sex in a good relationship, I would have chosen the latter. Sex is important in marriage, but that is not to say that a marriage be built on sex. If I had, let's say, an unfortunate accident which resulted in my being gelded, our marriage would certainly survive.
I noticed an earlier comment from a person who said that people like me have insufficient experience to comment on their choices. If so, such a person has quite the wrong sort of experience to comment on mine: you are either a virgin at marriage or you aren't. I made my choice, and I have no doubt that it worked well for me.