On April 6 he was very solemnly received at Erfurt. The large majority of the university there were by this time full of enthusiasm for his cause. His friend Crotus, on his return from Italy, had been chosen Rector. The ban of excommunication had not been published by the university, and had been thrown into the water by the students. Justus Jonas was foremost in zeal; and even Erasmus, his honoured friend, had no longer been able to restrain him. Lange and others were active in preaching among the people.
Jonas hastened to Weimar to meet Luther on his approach. Forty members of the university, with the Rector at their head, went on horseback, accompanied by a number of others on foot, to welcome him at the boundary of the town. Luther had also a small retinue with him. Crotus expressed to him the infinite pleasure it was to see him, the great champion of the faith; whereupon Luther answered, that he did not deserve such praise, but he thanked them for their love. The poet Eoban also stammered out, as he said of himself, a few words; he afterwards described the progress in a set of Latin songs.
The following day, a Sunday, Luther spent at Erfurt. He preached there, in the church of the Augustine convent, a sermon which has been preserved. Beginning with the words, of the Gospel of the day, 'Peace be unto you,' he spoke of the peace which we find through Christ the Redeemer, by faith in whom and in his work of salvation we are justified, without any works or merit of our own; of the freedom with which Christians may act in faith and love; and of the duty of every man, who possessed this peace of God, so to order his work and conduct, that it shall be useful not only to himself but to his neighbour. This he said in protest against the justification by works taught by most preachers, against the system of Papal commands, and against the wisdom of heathen teachers, of an Aristotle or a Plato. Of his present personal position and the difficult path he had now to tread, he took no thought, but only of the general obligation he was under, whatever other men might teach; 'I will speak the truth and must speak it; for that reason I am here, and take no money for it.' During the sermon a crash was suddenly heard in the overweighted balconies of the crowded church, the doors of which were blocked with multitudes eager to hear him. The crowd were about to rush out in a panic, when Luther exclaimed, 'I know thy wiles, thou Satan,' and quieted the congregation with the assurance that no danger threatened, it was only the devil who was carrying on his wicked sport.