"Whatever man uses without the fear of God, whatever he applies to the mere gratifying of his flesh, cannot fail to operate as a poison to the soul, however pleasant and salutary it may appear to be to the body"

This quote by Johann Arndt is a warning against the misuse of the things we have actually been provided. He is saying that if we use the important things we have actually been offered for our own self-centered desires, it will resemble a toxin to our souls, even if it may seem beneficial to our bodies. He is recommending that we must use the things we have actually been provided with regard and respect for God, and not just for our own enjoyment. He is advising us that we ought to bear in mind how we utilize the important things we have been offered, and that we must use them in such a way that honors God. By doing this, we can guarantee that our souls stay healthy which we are residing in a manner in which is pleasing to God.