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.

582. 'After the sons of God went in to the daughters of man, who bore children to them' means at that time when they immersed doctrinal matters concerning faith in their own evil desires and became Nephilim. This is clear from what has been stated and shown just above at verse 2, that is to say, 'the sons of God' means doctrinal matters concerning faith, while 'daughters' means evil desires. Nothing else is born of this union than their treating the holy things of faith as worthless and their profaning them. For a person's desires which stem from self-love and love of the world stand utterly opposed to all that is holy and true. Moreover evil desires prevail with man, and therefore when the holy and true which have been acknowledged by him are immersed in such desires he is done for, since these cannot be rooted out and dispersed. They cling to every one of his ideas, and in the next life it is ideas that are communicated from one person to another. Consequently as soon as any idea of what is holy and true is brought out, so too is the unholiness and falsity attached to it, which is perceived instantly. Consequently such people have to be separated and forced down into hell.