What does the Qur'an say about the treatment of infidels?

Answer 1

This question simply asks about "Treatment of Infidels", but not by whom, as a result this question is split between what Muslims as people are ordered to do to the Infidels in the Qur'an and what God says that He will do in the Qur'an to the Infidels. Further, while there are three categories of Non-Muslims in the Qur'an and Islamic theology (Kaafer, Mushrik, and Ahl al-Kitaab), for the purpose of treatment, there is really no distinction in the Qur'an save degree, (e.g. Kaafers are more repressed than Ahl al-Kitaab, but it is not that one group is treated positively and the other negatively). To read more about different types of infidels see this question.

Muslim to Infidel
This is a question of interpretation. The Qur'an is a very contradictory book.

There are those that argue that verses Q: 2:256 and Q: 109:1-6, both of which support tolerance of Non-Muslims, are the basis upon which Non-Muslims have the freedom to live and worship. This is a view espoused by a number of peaceful Conservative Muslims (a significant percentage / roughly half of the Islamic World) and by almost all Liberal Muslims (small minority, though they are). There are some moments in history where this interpretation was more prevalent, but it was generally a minority position, until today when tolerance and acceptance are considered desirable.

The other interpretation, which is adhered to by a number of peaceful Conservative Muslims, especially Islamists, and by warmongering Jihadists (small minority, though they are), is that Muslims have a superior position to Non-Muslims and have good grounds upon which to make that claim. Q: 3:19 claims that the only religion that is acceptable to God is Islam. Q: 3:110 claims that Muslims are the best people in all history. Q: 8:55 claims that those who disbelieve are the worst of animals. Q: 9:29 argues for the repression and inequality of Jews and Christians before Muslims. Q: 5:51 argues that Muslims should not trust in Non-Muslim political authorities. -- There are numerous other verses that promote the view that intolerance and inequality between Muslims and Non-Muslims is Divinely Supported, creating difficulty in rejecting it. Additionally, the Qur'an has numerous verses that are Anti-Semitic, Hateful towards Christians, and Hateful towards Polytheists.

God to Infidel
The Qur'an is unequivocal as concerns what God will do to Non-Muslims. Here, it is simply a question of degree. There is no place in the Qur'an that says that God loves or respects Non-Muslims and there are hundreds of verses that describe the torment in Hell that He has prepared for Non-Muslims. Some of these great lines include: Q: 22:19-22 that discusses how the body of the Non-Muslim will be melted by fire and pierced by rods to make them anguish, Q: 4:56 discusses how skins will be burned off of Non-Muslims in agony and then God will provide a new skin to repeat this process, Q: 2:4-7 argues that God has intentionally made Non-Muslims incapable of belief in order to torture them, and Q: 2:161: discusses God and the angels cursing Non-Muslims.