Paul has been discussing the wisdom of God (1 Corinthians 2:6–16). He ends this discussion by quoting from Isaiah 40:13. This verse confirms that, left to themselves, humans are unable to understand the wisdom of God. Paul directly connects the Lord
to Christ.
Only those who have the Spirit have the mind of Christ,
and are therefore able to understand the wisdom of God.
16 “For who has understood the mind of the Lord so as to instruct him?” But we have the mind of Christ.