Luther's teaching on the atonement [the "classical' or Christus Victor idea/motif] was not followed either by his contemporaries or by his successors...Without hesitation or delay they reverted to the Latin [legal, traditional, Latin model; penal substitution] doctrine....his idea of the atonement formed one organic whole with the central proclamation of the Reformation..
Obviously, Luther's contemporaries failed to understand his teaching on the subject, and they never grasped his deeper thoughts. They interpreted him from the first in light of the traditional belief, inherited from the Middle Ages. Either they failed to see the gulf...or in so far as they had some inkling of it, they did their best to cover it up..
..The inner tensions within Luther's theology, the vigour and force of his thoughts, and his sharply paradoxical language, Melancthon wholly lacked the power to understand." -Gustaf Aulen, Christus Victor, p. 124