Why Pietism offers little hope

I have been told by friends in Germany that the best, most biblical denomination is the Bund Freier Evangelische Gemeinden (FeG). If my experience on holiday in Kassel is any measure, then God help Germany!
The sermon was on John 10:27-30. The initial introduction set the text in its immediate context: what Jesus was claiming in claiming to be the Good Shepherd and God's equal was clear enough to His then listeners. So they picked up stones to stone Him.
Then we were taken through the text step by step:
"My sheep"
We were informed how valuable the sheep were to a shepherd, and how much he would do for them if he was both shepherd and owner, since they were his precious property. So we too are precious in the eyes of Jesus, because we are His sheep.
True, in fact, Jesus makes the point Himself really well in verses 11 to 15 of the same chapter (always take your Bible to church - you can preach to yourself the bits the minister leaves out!), by talking about the Cross. "I am the Good Shepherd. The Good Shepherd lays down His life for the sheep." Jesus even makes the point the preacher made about hired hands and shepherds! So why didn't the preacher make Jesus' point Jesus' way?
"My sheep listen to My voice"
Listening to Jesus' voice is not a matter of technique, we were informed. It's not about sitting quietly and calming oneself. Absolutely correct - we must knock this New Age or Eastern or Gnostic mysticism on the head when it gets into the church. But having started so well, the preacher lost it.
Firstly, he fully legitimated this Gnostic approach to listening to Jesus as one alternative. Then he said that this verse was a promise that all Jesus' sheep would hear His voice. But it's not a promise - it's a statement of a fact that comes as a sharp rebuke to the Jewish scribes questioning Him, as the context in verses 22 to 26 make clear. Thirdly, he suggested that there were other ways of hearing Jesus' voice, such as reading a good book or "wenn man etwas aus der Bibel ableitet". God's voice is not Scripture, according to this man, but whatever I take away from it. Good! Richard Dawkins, Chris Hitchens et al. has taken away the last four words of Psalm 14 verse 1a! Fourthly, he said we need to listen; he contrasted that to the German student tradition of Bibelarbeit - literally, "Bible work", working away at the text to understand it.
Now he's fully moved to the mystic position, which says that God works exclusively through non-natural means. I consider myself Reformed in my theology, and the Reformed position is that man is essentially good, but by consequence of the Fall totally depraved. Having made humans, God looks on the world and says it is "very good". We are essentially, that is, according to what is essential to what we are, good. That is how we are made. But that is shot through with fallenness, such that all of what was created good is corrupted by sin.
One consequence is that God pours out His Holy Spirit, who was there in Creation (Genesis 1:2), to make us what we are by creation. The natural means God has created are not inferior, but "very good". Now God has given us His word in a book. So we are to read it as a book. The work of the Holy Spirit is to make us better readers and believing and obeying readers, that is, to help us understand the book and respond appropriately, as we naturally would do if it were not for sin.
Having been denied hearing the Gospel of Christ crucified and having heard such dangerous mystic-leaning ideas on Scripture, I half switched off. He was orthodox on verse 28, but uninterestingly so. But I was not surprised at his comment on verse 29 "Wir sollen das nicht theologisieren" - we should theologise this. Just hear the confidence you can have in Jesus, that He won't lose you. But what does that mean, that He won't lose me? Help me understand that, speak to me a word about God, a logos about the theos, a theology!
Perhaps it was the emnity to theology that led to the earlier mistakes too.
If that's the best Germany has to offer, then Lord Jesus Christ, please raise up harvest workers, preachers who love Your word and proudly preach Your Cross, that Your people might not starve, but be led onto good pasture (John 10:9) across that nation.