There is a big difference between knowing and understanding. One can know facts and figures for instance, in preparation for a history test. Dates and locations of battles can be recalled - the knowledge is in tact. But in terms of the history, this knowledge pales by comparison to understanding what brought this battle about. What were the issues behind it, who were the personalities that drove it - essentially, "why" did it happen? If one grasps these latter items, they have begun to understand the history, not just know it. Memorizing the dates and locations was sometimes required for passing tests in school, but that level of understanding is quite one dimensional, as compared to say, three dimensional.
Math has a similar concept. As a more liberal arts and language type person, I struggled with math when it got to sophisticated concepts. Differential logarithms I remember, were my jumping off point. Because I didn't really understand the concepts, I was forced to try to pass the tests by memorizing the steps. I learned how to pass (barely) by practicing what I had memorized - but in reality - I didn't know what I was doing.
You could say that "knowing" is a one dimensional engagement, while "understanding" is a three dimensional engagement. Knowing might be the black and white version, while understanding is the color version. When we don't really understand something, we operate by trying to memorize the rules and then "just do the rules." When we really understand something, we can engage at a much deeper level. We can often "figure it out" even without the rules - because our level of understanding enables us to figure it out - sort of organically, sort of naturally. The people that are only operating at the rules level ask in amazement, "how did you know how to do that?" Or, "how did you figure that out?" The difference is between knowing and understanding.
I think there are a lot of Christians who know the bible but who perhaps don't understand it. I don't say this as criticism really, mostly I'd love to help if I could. This means that many Christians don't really understand the Christian life either - they just "memorize" it, or they just operate by the rules. This distinction becomes very clear in observing the way of Jesus and the way of the Pharisees. Jesus said, "their faith is in vain, their teachings are but rules taught by men." (Mt 15:9) This is what people do when they don't understand, they live a one dimensional engagement at the rules level. In the world of Christian faith, this generally becomes a cheerless and then lifeless regimen of rule following. It's far from the life Jesus lived and taught. The Christian life he taught was a richly textured, organic and intimate life with God. Jesus took the water of everyday life and turned it into wine. The Pharisees however were adept at the reverse, turning the rich life with God (wine) into a dirge of obligation (water). Another of the many examples of their differences can be seen in the arguments about Sabbath. To the Pharisees, the Sabbath was a hard law of prohibitive obligation, to Jesus it was life giving intimacy with God. Jesus said, "The Sabbath was made for man, not man for the sabbath." (Mark 2:2)
One could write many pages on this topic - but for blog purposes, I'll close with a final illustration. This one makes the distinction between "knowing and understanding" through a very different picture: Job's life. If you know the story, Job lived through remarkable suffering. The accounts are strong, poignant, and heartbreaking. Yet remarkably, they are life-giving. At the end of it all, after the suffering, the false friends, the arguments with God and the reconciliation - Job reflects on his life before his hardship and now after. He says, before all of this "my ears had heard of you, but now my eyes have seen you." Same idea - knowledge vs. understanding.
