What does 1 Corinthians 2:11 mean?
Paul has written that the only way for any human beings to know God's hidden wisdom, including God's plan for the salvation of believers, is for the Holy Spirit to reveal it to them. It cannot be figured out through human observation and wisdom. Those fallible means can give us intellectual knowledge (Psalm 19:1; James 2:19), but not trusting faith (Matthew 7:7–8).Now Paul describes God's Spirit working in a similar way to our own spirits. Nobody can use their human senses to know what other people are thinking, either (1 Samuel 16:7). Only our own spirit, and God, can be aware of our own thoughts. If our "spirit" does not tell what those thoughts are, they will remain secret.
In a similar way, nobody knows God's thoughts except His own Spirit. The difference is that, mysteriously, God can task His Spirit to come and reveal His thoughts and plans to us. That's the means by which we come to faith in Christ.