Martin Luther correctly identifies homosexuality with the sin of Sodom. Commenting on Genesis 19:4-5 he writes:

I for my part do not enjoy dealing with this passage, because so far the ears of the Germans are innocent of and uncontaminated by this monstrous depravity; for even though disgrace, like other sins, has crept in through an ungodly soldier and a lewd merchant, still the rest of the people are unaware of what is being done in secret. The Carthusian monks deserve to be hated because they were the first to bring this terrible pollution into Germany from the monasteries of Italy. (Luther’s Works, Vol. 3, 251-252)

And then in the same section of the Genesis lecturers, Luther refers to:

the heinous conduct of the people of Sodom ” as “extraordinary, inasmuch as they departed from the natural passion and longing of the male for the female, which is implanted into nature by God, and desired what is altogether contrary to nature. Whence comes this perversity? Undoubtedly from Satan, who after people have once turned away from the fear of God, so powerfully suppresses nature that he blots out the natural desire and stirs up a desire that is contrary to nature. (Luther’s Works, Vol. 3, 255)

See also:

JOHN T. PLESS: MARTIN LUTHER’S REJECTION OF HOMOSEXUALITY

ELCA AND HOMOSEXUALITY

MARTIN LUTHER SAYS NO…TO WOMEN PASTORS

MARTIN LUTHER ON FALSE TEACHERS

MARTIN LUTHER ON CONTEMPLATIVE SPIRITUALITY AND EMERGENCE CHRISTIANITY

THE NEW CHRISTIANS WITH CHRISTIANITY WORTH BELIEVING—NO SOLA SCRIPTURA: YES, WOMEN PASTORS AND QUEER CHRISTIANS

WHY NO CONDEMNATION FOR CHRISTIANS WHO ARE HOMOPRESSIVE?