Name Dropping: Saint Augustine (Saint Uh-GUSS-tin if you're trying to impress people; St. AWW-guh-steen if you're talking about the town in Florida): (354-430). The most important Christian theologian ever, except for St. Paul, whose thoughts on God ended up filling out the latter half of the New Testament. Augustine didn't get so lucky—but he still gets read by anyone seriously studying the Christian understanding of God.
When to Drop Your Knowledge: Adds heft to your religion debates. But more importantly: Augustine authored one of the greatest pick-up lines in history, which works today just as nicely as it worked in CE 400.
Born in Africa (in what is now Algeria), Augustine was raised a Christian but left behind the blessed life when he began attending school in Carthage, which was sort of the fourth century's South Padre Island. In his youth, Augustine fathered an illegitimate son, but by the age of 21, he began to get serious about spirituality. He undertook a deep and serious study of Philosophy, Theology, and religion while teaching school in Milan—and then, on Easter Day in the year 387, Augustine was baptized a Christian. The Church would never be the same.
A mere eight years after his conversion, he was Bishop of Hippo (the Algerian city, not the Hungry Hungry board game icon), a position he held for the rest of his career. Although said to be an unusually good preacher—he made his outlandishly complicated theology comprehensible to a lay audience better than anyone has since—Augustine made his real mark with his writing. Confessions, a memoir-cum-Christian-apologia, is required reading for Catholic and Protestant seminarians alike. On the Trinity did more to define the Christian understanding of the Trinity than any Church Council. And City of God, which we recommend reading if you have seven or eight free years, is a sprawling and beautiful defense of Christianity against paganism that is so incredibly and utterly long that many people have converted to Christianity just so they wouldn't have to keep reading it.
From the beginning, the Catholic Church embraced Augustine's work. But his radical emphasis on grace as the means to salvation would later inspire the likes of Martin Luther and John Calvin when they were asserting that faith alone leads to heaven. So, basically, everyone loved Augustine. Except of course the Manicheans, whom he helped destroy.
Pop Quiz: What's the name of the religious sect founded by a charismatic fellow who believed in baptism and ended up getting crucified? Why, Manichaeism, of course. Founded in the 3rd century by a Persian named Mani who was eventually crucified for his beliefs, Manichaeism stressed the duality of good and evil and claimed to have successfully synthesized all the world's major religions. Although Manichaeism survived in Turkey and the Middle East until after 1000 CE, it was eventually overtaken by Islam and Christianity. We're just grateful Mel Gibson isn't a Manichean, because as gory as his "Passion" was, Mani's story was even worse: After being crucified in 276 by a Persian Emperor, Mani's body was flayed, gutted, stuffed, and hung up at the city gates as a warning to his followers.
Because Augustine's work was immediately considered so significant, a lot of his writing has survived—about 5,000,000 words, in fact. (That's approximately 100 of these books.)
There's a pervasive rumor that St. Augustine invented the phrase "missionary position." This is simply untrue. (However, there are vague statements in Augustine's writing that imply he believed the missionary position was the least sinful.) So where did the phrase "Missionary Position" come from? Its first use appears to have been in about 1969—probably by some counterculture kids who were ridiculing the position as boring and prudish.
Augustine is called one of the "Four Great Fathers of the Latin Church," but that's a little like saying that all four Beatles were created equal. Of the Four Fathers (the other three are the less-great and less-famous Jerome, Ambrose, and Gregory the Great), Augustine's importance far outstrips the others. He's Paul and John—so Augustine's the only fourth-century name you need to drop.
Augustine is so important that his mom got sainted (she's St. Monica), mostly for doing such an excellent job raising him. Augustine's dad, on the other hand, is not a saint. He is remembered primarily for cheating on St. Monica.
And finally, the pick-up line! In his memoir Confessions, Augustine recounts that he would pray, "Lord, make me chaste—but not yet." As Augustine well knew, this works great as a pick-up line. Nothing makes someone feel special like ripping off your habit or priestly collar and saying, "Lord, make me chaste—but not yet."
Fake your way through any conversation. All you need is Cocktail Party Cheet Sheets, the mental_floss book by John Green.