In our culture, pregnant unmarried teenage girls hardly draw notice. Indeed, some teens sport pregnancy as a badge of honor. Society's answer is “safe sex”; celibacy is essentially a dinosaur, abstinence simply isn't “cool.” In first-century Israel, this was not the case. Jewish teenage girls did not turn up pregnant without the burden of shame. So when Joseph got word his young fiancée was pregnant, presumably with another man's child, he prepared to break off his engagement (Matthew 1:18-25).
Think of the humiliation for a righteous Jewish man, deeply concerned about matters of purity and appearance, to have a pregnant girlfriend. What about family and neighbors, especially brothers and sisters at the local synagogue?
We don't get it, those of us hardened by the tolerance of the modern world. What's the big deal? It's only about private matters of sex. Well, it mattered to Joseph; so he tried to bow out gracefully, without bringing shame upon his young bride to be. But God had other ideas. Tell Joseph it's not another man; indeed the Holy Spirit is responsible. Who's going to believe that one? The brothers down at the synagogue will find the explanation a stretch, “Sure Joe”; the sisters will only blush. But Joseph toughed it out. Why? Because he was a righteous man. This means he was not only a moral man who did not get teenage girls pregnant but a faithful man who implicitly trusted God at his word, even when it seemed bizarre to do so. It may have been a bad day at Joseph's house, but it was a great day for the world.