There were a number of factors unrelated to science that contributed to Galileo's condemnation by the church. Historically the church had been fairly tolerant towards scientific challenges, being willing to alter interpretations of scripture when it was deemed necessary. However, the Catholic church at this time was battling the rise of Protestantism and one of the main points of contention was who had the authority to interpret scripture. The Catholic church maintained that only official church theologians had this authority. Galileo had suggested that a moving earth did not contradict the scriptures since the Bible often uses metaphors when speaking of natural events. Therefore, they felt that it was dangerous at this time to allow a layman such as Galileo to dictate how certain passages of scripture should be interpreted. This may be one of the reasons that the church took a tough stand when dealing with Galileo. In addition, Galileo made a number of political blunders. Initially the Jesuits had been strong supporters of Galileo. They had confirmed his observations with the telescope and had enthusiastically endorsed him to the officials in Rome. . However, starting in 1611, Galileo began studying the motion of sunspots (small dark spots on the surface of the sun). These were observed independently by a prominent Jesuit astronomer, Christopher Scheiner. Scheiner believed that these spots were small dark objects orbiting the sun at some distance. Galileo believed that the evidence pointed to the spots being on the surface of the sun. Galileo published his results in 1613 and asserted his priority of discovery. This angered Scheiner.
In 1618 three new comets were observed. Orazio Grassi, a prominent Jesuit mathematician, wrote a book using the pseudonym Lothario Sarsi that discussed the comets. In this book he argued that comets followed paths close to those of planets, but had shorter lifetimes. Galileo knew from his observations that comets moved in a straight line most of the time. In a 1623 publication, The Assayer, Galileo offered support for his position and made the following degrading remark concerning Sarsi
In Sarsi I seem to discern the firm belief that in philosophising one must support oneself on the opinion of some celebrated author, as if our minds ought to remain completely sterile and barren unless wedded to the reasoning of someone else. Possibly he thinks that philosophy is a book of fiction by some author, like the Iliad or Orlando Furioso — productions in which the least important thing is whether what is written in them is true. Well, Sarsi, that is not how things are. Philosophy is written in this grand book the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and to read the alphabet in which it is composed. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures, without which it is humanly impossible to understand a single word of it; without these one wanders about in a dark labyrinth.
This attack on one of their own further angered the Jesuits. Galileo, in his writings, would often seek to destroy his opponents as well as their arguments.
As was mentioned previously in the introduction, Galileo's biggest enemies were from the academic community. Aristotle was treated as a hero in academic circles, and Galileo's attacks on Aristotelianism were met with considerable resistance. In addition Galileo chose to publish in Italian, the language of the people, rather than in Latin as was the norm in academic publications. It is probable that some of the academics used their influence to incite the church against Galileo.
The sun-centered model of Copernicus received little attention by the church in the years following its release. This was probably due to the fact that most viewed it as a computational device and not as a representation of reality. However, the attention paid to it by Galileo caused some concern. The Copernican system was condemned by the church in 1616. The Pope asked Cardinal Bellarmine to convey news of this condemnation to Galileo. Bellarmine was the chief theologian of the church. Galileo met with Bellarmine and was given an affidavit that stated that Galileo was to no longer to hold or defend the propositions that the earth moves and the sun doesn't. Bellarmine himself didn't seem to be completely closed-minded on the subject. In a letter to a friend he once stated
Third, I say that if there were a true demonstration that the sun is at the center of the world and the earth is in the third heaven, and that the sun does not circle the earth but the earth circles the sun, then one would have to proceed with great care in explaining the scriptures that appear contrary, and say rather that we do not understand them than what is demonstrated is false. But I will not believe such a demonstration, until it is shown me.
This doesn't sound like a mindless rejection of the Copernican system. Unknown to Galileo, an unsigned memo was given to the Pope that supposedly came from the meeting with Cardinal Bellarmine. It stated that Galileo was no longer to hold, defend, or teach the aforementioned propositions. The inclusion of the word teach was important since it meant that Galileo could not even describe the Copernican system. This memo would show up later in the trial of Galileo. It is possible that this unsigned memo was produced by some of Galileo's enemies.
In 1623 Mafeo Barberini became Pope Urban VIII. Barberini was an admirer of Galileo and once had confided to him his pet theory that even though the universe may be most simply understood by thinking the sun at rest, God could have arranged it that way, but with the earth at rest. With his friend and admirer now the Pope, Galileo felt more confident in arguing for the Copernican system. In 1632 he published a document in which he disguised his position by presenting his arguments as part of a three person dialogue. It was titled Dialogue Concerning the Two Chief Systems of the World — Ptolemaic and Copernican. One of the participants in this dialogue was named Salviati. He was the spokesman for Galileo and presented brilliantly the case for Copernicanism. The second participant was named Simplicio. He represented an Aristotelian professor who was portrayed as ill-informed and not very bright. The name Simplicio is very close to the Italian word for simpleton. The third participant was named Sagredo. He represented an open-minded unbiased observer. Towards the end of the dialogue Galileo made the mistake of putting the statement of the Pope's pet theory in the mouth of Simplicio, the simpleton in this dialogue. It is unlikely that Galileo was trying to ridicule the Pope, but he may have thought that no one would notice. However, Galileo's enemies picked this up quickly and convinced the Pope that he was being ridiculed. The Pope was not amused. In August of 1632 the Inquisition in Rome issued an order to stop the publication of the Dialogue, and Galileo was ordered to stand trial. The trial was not about the scientific merits of Galileo's views, but was about whether Galileo had disobeyed an official order. The unsigned memo was issued as evidence, but Galileo denied ever receiving a copy. Three officials reviewed the Dialogue and agreed that it did advocate Copernicanism. In an unusual move, it was suggested that Galileo could get off with a lighter sentence if he would admit some wrongdoing. He agreed to remove any parts the Dialogue that seemed to advocate Copernicanism and he admitted that he had gone too far in some of his arguments. He was sentenced to house arrest for the rest of his life, most of which was spent in his large villa near Florence. Three of the ten Cardinals involved in the inquisition did not sign the verdict. In the few years that remained of his life he made a number of important contributions to mechanics. Certainly the trial of Galileo was an unfortunate event that involved mistakes by both the Catholic church and by Galileo. However, to view this as a battle between science and Christianity is much too simple. There were a number of other factors involved. Science was undergoing a major paradigm shift and the church was facing significant opposition from the Protestant movement. Galileo shares some of the blame for the way he treated those who disagreed with him. It should also be noted that Galileo himself was a committed Christian before the trial and remained one afterwards.
The paradigm shift in science forced Christian theologians to reexamine verses that seemed to support a stationary earth. Today these verses are viewed differently. For example, 1 Chronicles 16:30
Tremble before him all the earth! The world is firmly established; it cannot be moved.
is seen as a poetic or metaphoric way of describing the stability of God's creation. Other verses such as Ecclesiastes 1:5
The sun rises and the sun sets, and hurries back to where it rises
are seen as using phenomenological language. Certainly, the purpose of these verses was not to advocate some astronomical theory. The reinterpretation of these scriptures did not affect any major Christian doctrine.