Like so many common verbs, the meaning of "know" in the Bible is varied and dependent on context. And in some cases -- when it is connected to ideas or objects -- its spiritual meaning and natural meaning are essentially the same. When the Bible talks about people knowing each other and especially when it talks about the Lord knowing people, the meaning has more to do with the states of love within people than it does with any factual knowledge. This makes sense if you think about it. When we really "know" somebody, what we mean is that we know what kind of person they are, what their motivations are, what they love, what they hate, what makes them tick. Those things are far more important than knowing their parents' names, where they were born or what year they graduated from school. Most often then, especially applied to people, "knowing" has to do with the perceptions we have about other people's loves and the conjunction that can exist between those with similar loves, not just a collection of facts.

8394. Having examined himself, acknowledged his sins, and repented a person must remain steadfast in good to life's end. But if having done those things he falls back into his former life of evil and embraces it he profanes that good since he now links evil with it. As a consequence his latter state becomes, according to the Lord's words, worse than his former,

When the unclean spirit goes out of a person he goes through dry places seeking rest, but does not find it. Then he says, I will return into my house from which I came out; and when he comes and finds it empty, swept, and decorated for him, he goes away and links to himself seven other spirits more evil than himself; and they enter and dwell there. And the latter [circumstances] of the person become worse than the first. Matthew 12:43-45.