In other words, the Spirit of God is supplied to us so we can pray in the Spirit. And Paul says that that supply of the Spirit comes by hearing with faith. We hear a promise: “I’ll help you. I’ll strengthen you. I’ll hold you up in prayer with my Holy Spirit.” And we believe it. We believe it. And by that faith, the Spirit moves to create and sustain and guide our praying.

So, my answer to the question is that praying in the flesh would be praying without faith in the promise that the Holy Spirit will prompt and guide our prayers. And praying in the Spirit means we trust the promise of God’s help, by the Spirit, so that through this faith, the Holy Spirit is supplied and our prayers are moved and guided by the Spirit. What a gift.