To be "Known" by someone.

To be known by someone implies a degree of intimacy, marked by close acquaintance, association, or familiarity.

I am reminded of a verse I used to misquote. "My sheep hear my voice and they follow me". In fact most people will misquote it that way.

The actual verse is...
John 10:27. My sheep hear My voice, and I know them, and they follow Me;

This is in stark contrast to a verse where Jesus makes another statement about knowing someone.

Matthew 7:21:23  “Not everyone who says to Me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of My Father in heaven. 22 Many will say to Me in that day, ‘Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?’ 23 And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness!’

I never knew you?

Matthew 7:21-23 (NKJV)
21 “Not everyone who says to Me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of My Father in heaven. 22 Many will say to Me in that day, ‘Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?’ 23 And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness!’
How can God not know someone?