Robert Sungenis vs. Justification being forensic

If justification were a mere legal transaction between God and man (e.g., like a modern will), we would not need continual intercession by Christ to complete our salvation . . . [Protestants] when pressed to follow their forensic model to its logical conclusion, cannot adequately explain why personal faith is required for justification, given that faith is a non-legal and timeless virtue. Moreover, most have no explanation why the New Testament, especially the book of Hebrews, repeatedly warns Christian not to fall away from the Faith, other than claiming that such a person was never legally justified. (Robert A. Sungenis, Not by Bread Alone: The Biblical and Historical Evidence for the Eucharistic Sacrifice [2d ed.: Catholic Apologetics International Publishing, 2009], 62).