Watchman Nee emphasizes that God desires us to be continuously empty in order to be filled with the Holy Spirit. He illustrates this through the story of a woman who had only a pot of oil, highlighting that the more we empty ourselves, the more room we create for God's fullness. The sermon teaches that our responsibility is to keep emptying ourselves, while God's role is to fill us with His Spirit. Nee reminds us that God waits for us to recognize our need for Him, and only those who acknowledge their emptiness will be filled. Ultimately, the message is about the importance of maintaining an open heart to receive God's abundant blessings.