Luther actually referred to the teaching of the soul being immortal as part of a dung hill
Then, on October 31, 1517, Luther posted his famous Theses on the church door in Wittenberg. In his 1520 published Defence of 41 of his propositions, Luther cited the pope’s immortality declaration, as among “those monstrous opinions to be found in the Roman dunghill of decretals” (proposition 27). In the twenty-seventh proposition of his Defence Luther said:
However, I permit the Pope to establish articles of faith for himself and for his own faithful—such are: That the bread and wine are transubstantiated in the sacrament; that the essence of God neither generates nor is generated; that the soul is the substantial form of the human body that he [the pope] is emperor of the world and king of heaven, and earthly god; that the soul is immortal; and all these endless monstrosities in the Roman dunghill of decretals—in order that such as his faith is, such may be his gospel, such also his faithful, and such his church, and that the lips may have suitable lettuce and the lid may be worthy of the dish.—Martin Luther, Assertio Omnium Articulorum M. Lutheri per Bullam Leonis X. Novissimam Damnatorum (Assertion of all the articles of M. Luther condemned by the latest Bull of Leo X), article 27, Weimar edition of Luther’s Works, vol. 7, pp. 131, 132 (a point-by-point exposition of his position, written Dec. 1, 1520, in response to requests for a fuller treatment than that given in his Adversus execrabilem Antichristi Bullam, and Wider die Bulle des Endchrists).