1 Corinthians 2:11

‘For who among men knows the things of a man, except the spirit of the man which is in him? Even so no one knows the things of God, except for the Spirit of God.'

A man's true self and inner knowledge and very being is only known to that man, deep inside through his ‘spirit', that inner part which is the seat of his understanding and consciousness and spiritual experience. Others may think they know him but the deepest things, the things which are essentially him, are hidden; known, in so far as they are known at all, only to him. The verb for ‘know' is oida, knowing intellectually. He knows himself but he does not truly ‘know' (ginosko) himself. In a similar way God's true self and inner knowledge and very being is known only to God, deep within Him, in His Spirit. But this time it is known (ginosko) to the full, intellectually and experientially. And this is the Spirit that we have received if we are His, the One Who knows God in every way. For if any man does not have the Spirit of Christ, he is none of His (Romans 8:9). And to have received the Spirit is to have received the One Who holds all the secrets of God, and reveals them to the heart as we are receptive to them.

This is to be seen as a play on ideas rather than as suggesting that man's make up is like God's, as the change of verbs also indicates, for the whole point is that God's Spirit actually comes to us and brings us the revelation of what He Himself is (whereas our spirits remain within us as part of us). It is not to be seen as like and like.