Martin Luther is of course well known for starting the Protestant Reformation. The Roman Catholic Church had become very rich, powerful and corrupt, and the Reformation not only returned Christianity to its biblical roots, it ultimately forced the Roman Catholic Church to reform itself. Martin Luther did a lot of good for Christianity, and without him the western world would be unrecognizable today. Perhaps the Renaissance and the Enlightenment may have been still born or seriously limited, in addition obviously to the Reformation.
Of course Martin Luther was not perfect, and his quotes against women and Jews are well known. It is likely that Hitler's antisemitism was based in part on Martin Luther's attitude to the Jews, although Hitler claimed to be a Roman Catholic, as well as a misunderstanding of human evolution, thinking that some races were more evolved than others. We now know this to be false. Martin Luther is also well known for the dogma of Sola Scriptura, i.e. Scripture Alone, which was a reaction against many of the traditions of the Roman Catholic Church, such as indulgences.
Young earth creationists in the USA today like to cite Martin Luther and the dogma of Sola Scriptura, if only implicitly, in their belief that the universe is only about 6000 years old. When such creationists are reminded that the church opposed heliocentricism, Galileo's fight with the Roman Catholic Church is always brought up, and in their defense they point out that geocentricism was "pagan" Aristotelian philosophy, and the Roman Catholic Church was involved. They conveniently forget that the Greek philosopher (another pagan!) Aristarchus of Samos was the first known person to propose heliocentricity around 200 BC. They also forget that Martin Luther and the other early reformers also opposed heliocentricism. Although Sola Scriptura can be a valuable theological tool in interpreting the Scriptures, it is a big mistake to extend its use outside Scriptures. Living at a time when science as we know it was just starting, Martin Luther can at least be excused, but this cannot be said of the modern creationists.
One very common theme running through young earth creationist arguments is the implicit "sin" of thinking for yourself and using the brains God gave you. It is supposedly sinful to use autonomous human reasoning, so when the Bible says something, you are just to accept it without question, regardless of reason, logic or the evidence, i.e just be a good Christian and follow unquestioning belief. Many passages in the Bible are taken out of context to support this view. A recent quote I had thrown at me is Psalms 118:8 "It is better to trust in the LORD than to put confidence in man". This kind of game is played a lot by the young earth creationist movement AiG (Answers in Genesis - http://www.answersingenesis.org). This "sin" of using reason crops up in several quotes from Martin Luther and John Calvin, as emphasized by red in the quoted texts below.
In defense of a literal 6 day creation and a 6000 year old universe, AiG have the following citation from Martin Luther:
“When Moses writes that God created heaven and earth and whatever is in them in six days, then let this period continue to have been six days, and do not venture to devise any comment according to which six days were one day. But, if you cannot understand how this could have been done in six days, then grant the Holy Spirit the honor of being more learned than you are.”
- Martin Luther, What Martin Luther Says: A Practical In-Home Anthology for the Active Christian.
However, creationist conveniently forget about this quote from Martin Luther:
"Scripture simply says that the moon, the sun, and the stars were placed in the firmament of the heaven, below and above which heaven are the waters... It is likely that the stars are fastened to the firmament like globes of fire, to shed light at night... We Christians must be different from the philosophers in the way we think about the causes of things. And if some are beyond our comprehension like those before us concerning the waters above the heavens, we must believe them rather than wickedly deny them or presumptuously interpret them in conformity with our understanding."
- Martin Luther, Luther's Works. Vol. 1. Lectures on Genesis, ed. Janoslaw Pelikan, Concordia Pub. House, St. Louis, Missouri, 1958, pp. 30, 42, 43.
This belief is consistent with the ancient Middle Eastern, including Hebrew, belief that the sky was a solid dome with water above it. The firmament or sky in Genesis in the original Hebrew is "raqia", which refers to beaten metal. Another quote attributed to Martin Luther is the following:
"People gave ear to an upstart astrologer who strove to show that the earth revolves, not the heavens or the firmament, the sun and the moon. Whoever wishes to appear clever must devise some new system, which of all systems is of course the very best. This fool [or 'man'] wishes to reverse the entire science of astronomy; but sacred Scripture tells us that Joshua commanded the sun to stand still, and not the earth."
- Martin Luther, Table Talk
John Calvin also believed in geocentricism, see this quote:
"Those who assert that 'the earth moves and turns'...[are] motivated by 'a spirit of bitterness, contradiction, and faultfinding;' possessed by the devil, they aimed 'to pervert the order of nature.'"
- John Calvin, sermon no. 8 on 1st Corinthians, 677, cited in John Calvin: A Sixteenth Century Portrait by William J. Bouwsma (Oxford Univ. Press, 1988), A. 72
Another quote is this one:
"The heavens revolve daily, and, immense as is their fabric, and inconceivable the rapidity of their revolutions, we experience no concussion -- no disturbance in the harmony of their motion. The sun, though varying its course every diurnal revolution, returns annually to the same point. The planets, in all their wandering, maintain their respective positions. How could the earth hang suspended in the air were it not upheld by God's hand? (Job 26:7) By what means could it [the earth] maintain itself unmoved, while the heavens above are in constant rapid motion, did not its Divine Maker fix and establish it? Accordingly the particle, ape, denoting emphasis, is introduced -- YEA, he hath established it."
- John Calvin, Commentary on the Book of Psalms, Psalm 93, verse 1, trans., James Anderson (Eerdman's, 1949), Vol. 4, p. 7
Using just Sola Scriptura as did Luther, Calvin, and many others in the church, one cannot avoid believing in geocentricism. So to be consistent, the people at AiG and ICR (Institute for Creation Research - http://www.icr.org) have to accept geocentricism. This is exactly what the geocentric creationists at http://www.fixedearth.com believe, and cite Scripture to back it up.
When Galileo turned his telescope to the sky, some in the Roman Catholic Church accused him of desecrating the sky with his telescope. The argument being presumably that only knowledge obtained from the Bible is true, and it was somehow sinful to gain knowledge from other sources. Implicitly at least, young earth creationists still follow this same line of thought. When Galileo discovered the four large moons of Jupiter, which are now known as the Galilean Moons, some in the church denied that he really saw the moons, and that they were some sort of an illusion perpetrated by Satan or demons. Many young earth creationists today follow a similar line of reasoning concerning distant astronomical objects, implying that some sort of an illusion is taking place, because the light travel time is very much longer than that allowed by a 6000 years old. Indeed, I have personally been told that all astronomers are deceived!
Long after Galileo's death the Roman Catholic Church eventually dropped their objections to heliocentricism as the evidence became so strong, but it was not until the 1990s that Galileo was formally exhonorated. The church is engaged in genuine astronomical research, see http://clavius.as.arizona.edu/vo/R1024/VO.html. Young earth creationists have not learned from the mistakes of the Roman Catholic Church. Will it take them another 400 years to admit they are wrong?