The danger is also that we remove faith from the concrete of the means of grace and the work of the Spirit from those means of grace so that even God becomes an idea to inhabit the imagination rather than the God who fills the present so that He might fill eternity with us. The more we distance God from the means of grace the more we distance Him from anything we would call real and unchangeable. God is not an idea. He is a personal being who is known to us in a personal way through the concrete of the Word and Sacraments. Faith is not an idea or even an idea of this God. Faith is the trust in the God who has revealed Himself to us and made Himself known to us precisely because without His aid and Spirit, we would be left to a mere idea of Him and not the reality of Him and what He has accomplished for us.
Of all the things that are dangerous to Christianity, one of them is surely the idea that we turn God on and off like a feeling, that we decide for Him or against Him at will and whim, and that He lives in us as an idea in our imagination. No God like this has any power to save us eternally nor has He the power to change us in the present moment. Such a God does not need to be worshiped, is hardly with the time to pray, and will countenance our surrender to whatever desire we have -- including the one to disown Him when He no longer is needed or fulfills any purpose in our eyes. This God is not the God of Abraham, Isaac, and Jacob, not the God of the prophets, and not the God who was made flesh in Jesus Christ. While I can only hope that evangelicals will tire of this view of God, I can warn the Lutherans who want to be like the evangelicals that this is not the God of our confession, not the God of our liturgy, and not the God of our prayers.