Students at Oral Roberts University in Tulsa, Oklahoma, don’t have a Gator Chomp or a Tomahawk Chop, but they do have an O: Whenever Oral Roberts would walk onto the stage at the school chapel, students would stand up, raise their arms into the shape of circles over their heads, and shout, "OOOOOOOOOOO!"

I attended ORU during my sophomore year of college, having had a charismatic Christian conversion experience right after high school. I couldn’t remain at the school for reasons of finances and faith—having a shortfall of both—but I’ve always had bright memories of the day Roberts spoke at chapel. For ORU students as for a great many Pentecostal Christians—the fastest growing segment of Christianity in the world—Oral Roberts, who died at 91 years old yesterday, was always something to cheer about.

If you don’t know who Roberts is, consider how three of his university’s students paint a picture of the man’s milieu: Kathy Lee Gifford, Joel Osteen, and Ted Haggard all attended ORU (only Haggard graduated). Gifford’s singing talent and on-camera composure were not uncommon at the school, where televised arts and entertainment for Christian ministry was a heavy educational focus. Osteen and Haggard replicated Roberts’ warm, down-to-earth speaking style and relentlessly positive messages, and they are but two of thousands of Christian ministers who consciously modeled themselves on Oral Roberts. At one time, between the 1950s and 1980s, Roberts was second only to Billy Graham among Christian leaders, and he was, like Graham, a visionary minister with a particular expression of the Christian gospel.

That expression will be Roberts’ legacy—more than his school, his pioneering work in television ministry, or the memory of his high profile failures in the 1980s, including a debt-ridden City of Faith medical complex and a related embarrassment surrounding his 1987 claim that God would "call me home" if he failed to raise $8 million. Future historians will footnote all that, and be more interested in Roberts’ theological ideas and how they reshaped Christianity.

Roberts had one life message, summed up in a variety of sayings as he preached over the years: "Something good is going to happen to you." "God is a good God." "All things are possible." "Expect a miracle." These sayings are a picture of Christianity imbued with the power of positive thinking, and they represent the life work of Oral Roberts.

These days, with Osteen offering Your Best Life Now and Pentecostal believers around the world embracing a version of Christianity that promises physical health and material wealth (of which, more below), it might be hard to imagine how fresh "God is a good God" must have seemed four or five decades ago. But it was a catchy clarification of an idea with which Christians had not always been in close contact, given previous generations’ emphasis on Calvinist doctrines of human depravity and a judgmental God. Of course, the Calvinist God was (and is) technically good, too, but Robert’s seemed extra good. Or only good.

A closer look shows that the God that Roberts preached had subtleties, too. The titles of Roberts books—there are over 130 of them!—reveal his focus on a God who is not only good, but nearly desperate to shower blessings on believers…if only they will exercise faith. One of Roberts’ core concepts was "Seed Faith," a notion that if you sow a financial seed through giving, you will reap financial fruit. As a matter of open-handed Christian giving and an accompanying trust that God will provide, Seed Faith is basic Christian discipline. But Seed Faith is rarely that simple, promising as it does an automatic, material return on a material investment—more like a (pre-recession) 401(k) than a mature spiritual practice. It issues a guarantee that life with God can be perfect, physically and materially without want. Somehow, "Something good is going to happen to you" quickly turns into "Nothing bad is going to happen to you."

Seed Faith and the prosperity gospel that Roberts popularized and propagated is developing an increasingly vexing legacy: sociologists such as Peter Berger have argued that prosperity teaching can be instrumental in pulling people out of poverty, especially in the southern hemisphere where the doctrine has been imported wholesale. But as this brief documentary by Nathan Clarke shows, prosperity teaching can take the form of a wishful and magical thinking with few discernible roots in Christianity’s scripture or historical witness. Within our own borders, prosperity thinking is now being blamed for the collapse of some portions of the housing market—a complicated claim, but one with enough merit to give Christians pause.

Is this Oral Roberts’ legacy? It’s certainly part of it, an unfortunately difficult admixture for a life that will receive a bounty of encomiums from some Christian quarters in the days to come. I have several friends who graduated from ORU—the people I met in my one year there were some of the finest I have had the pleasure to know (and most of them have long since shed the prosperity gospel from their faith). Tonight, I’ve watched them honor Oral Roberts on Facebook and Twitter as a "great inspiration" and "obedient servant." There are a thousand more of those, and they are, indeed, honorable things to say. But I’m hoping the conversation about Roberts, especially among his devotees, won’t end there. It’s perhaps fitting that Roberts died in the same year that the Lausanne Movement, an international group of Christian ministers and theologians, issued its statement on prosperity teaching—a level-headed look at the complicated gains of that teaching, but one that demands it be left behind for a truer gospel. That is a great place for the conversation about Oral Roberts to begin.