I wasn't exactly sure what he thought would happen if I admitted to my supposed One Sin. Would Ingrid be instantaneously healed of her seizures and developmental delay? Would the heavens part and the Hallelujah chorus sound as our family embarked on a new life of sinless bliss and ease, never again to offend God in word, thought, or deed?
I'm not implying that sin is never the cause of illness or misfortune. Of course a besetting sin against our own bodies can lead to physical problems. Relational sins can break families apart. Financial irresponsibility can lead to disaster. Actions have consequences. That's the way the world works.
But that does not mean that people who suffer are greater sinners than others. This is a very important distinction, and Jesus made a point of explaining it to his disciples. Some Galileans had been tortured by Pontius Pilate, and Jesus said, "Do you suppose that these Galileans were greater sinners than all the other Galileans because they suffered this fate? I tell you, no, but unless you repent, you will all likewise perish." (Luke 13:2-3)
Note that Jesus is drawing a connection between sin and suffering. There is a curse, incurred in the Garden of Eden as a result of sin, but the entire human race and all of creation is under it. We live in a fallen world, and everybody suffers as a result. For example, the current economic crisis was caused by widespread greed, but some of the nicest people I know have lost their jobs. Meanwhile, the very rich are still very rich--although maybe less so. Sin equals suffering, but not in any way that can be considered equitable. Let's say my cocaine habit caused Ingrid's disabilities; that still wouldn't have been fair to her. She certainly did nothing wrong. Sin causes indiscriminate suffering.
There is, however, some scriptural basis for uncovering sin before praying for healing, not in order to assign blame, but because we need to approach God in true repentance before his Holy Spirit can fill us. Sin separates us from God; repentance and faith unites us to him. But that's not to say that the suffering was punishment from God or that it was directly caused by sin. Nor are our past sins of great spiritual significance (unless they have a present impact). It only means that the same power that sanctifies also heals, namely the Holy Spirit. We can't be led by the Holy Spirit and simultaneously hold onto known sins, no matter how small and "understandable." It is God's presence that heals us, body and soul, but only if we let him fill every part of our lives.
Although the man at the healing conference had an offensive manner, his theology would have had some appeal if it were accurate. Who wouldn't be willing to put up with harassment from a stranger if it magically took away some terrible suffering? But God wants far more than that--he wants us to surrender all our sins, not just once, but continuously. That is much harder. But he is endlessly patient with us and works in our circumstances to bring us closer to that one goal: sanctification.
Jesus became the curse for us, to set us free from the power of sin and death. And in the words of "Joy to the World," he "comes to make his blessings flow far as the curse is found."