Imagine you get engaged to the girl of your dreams. Your wedding day was glorious and momentous and a time of great happiness and celebration for everyone involved. Nothing could be better. Come your wedding night, with eager anticipation you get ready for bed, ready to be with your Bride for what is to be the first time. However as you go to be with her, she stops you and says this, "I only want to know you intellectually. I just love figuring you out, learning about you, and reasoning with my friends about who you are. You are so famous and great, I absolutely love getting to know you. I can't wait to spend the rest of my life making plans with you and seeing what you have for me."
So it is with all people who only seek to know God with their minds and not be united with Him in Spirit as husband and wife become one flesh. Reason is insufficient to knowing God. Just as a wife will never truly know a husband unless she lies with him, so to a Christian will never truly know Christ unless He indwells within her. There no real union between Christ and the Church without the indwelling of the Holy Spirit.