Paul calls it a rival doctrine, an addition, an occasion of stumbling, an offense and a byway, when one establishes the conscience upon his own goodness or deeds. The doctrine of earning entrance into heaven by virtue of fastings, prayers and penance is a branch road, which the Gospel will not tolerate. If only I am directed into a branch or parallel road, then my soul is turned from God upon that road, where I must perish. Thus this road is the cause of my death. The conscience and heart of man must be founded upon one single Word or they will come to grief.
All flesh is grass, and all the goodliness thereof is as the flower of the field.
There is no help nor remedy. The foundation is laid upon which the conscience may be established forever. The words of men must perish and everything that cleaves to them. He then opens to the shepherd, that is, to Christ the Lord, and lets him alone feed the sheep. The lamb then hears Christ's voice and follows it.