On the recommendation of his teacher, he came to Coburg in 1544 as a court preacher ( Hofprediger ) and visited the city’s churches and schools on the behalf of the Duke of Saxony.
After Maximilian graduated in 1546 under Caspar Cruciger the Elder at Wittenberg to the rank of Doctor, he was appointed as a Superintendent.
He fought against Andreas Osiander and helped in 1556 to enforce the Reformation to the Margraviate of Baden-Durlach on the behalf of its ruler, Charles II.
As the Spiritual Assessor for the Consistory of Weimar, he pleaded in 1561 for peace with the terms of the mediating theologian Melanchthon.
A year later, Mörlin was appointed to Dillenburg and later Siegen, where he represented his side against the Reformed tendencies of the ruler, the Count of Nassau-Dillenburg, John VI, but without success.