Since the allies of Allah are the pious believers, and people are of various degrees in faith (imaan) and pious practice (taqwa), it is clear that people are also of varying degrees of closeness (wilaya) to Allah ta'ala in accordance to their degree of faith and pious practice. In the same way, just as they are of varying degrees of disbelief (kufr) and hypocrisy (nifaaq), they are also of varying degrees of distance from and enmity of Allah in accordance with that.
The basis of faith and pious practice is the belief in the prophets of Allah, and the consummation of that is the belief in the Seal of the prophet, Muhammad - may the peace and prayers of Allah be upon him. Faith in the Prophet includes the faith in all of the books of Allah, and His prophets. On the other hand, the basis of disbelief and hypocrisy is the rejection of the prophets of Allah and the messages which they brought. This is the disbelief for which its proponent deserves punishment in the hereafter, since Allah has informed us that He will not punish anyone except after the delivering of the message. Allah said:
[We are not about to punish (anyone) until we have sent a messenger.] Qur'an 17/15
[We have given revelation to you as we gave it to Nuh and the prophets who came after him, and We gave revelation to Ibrahim and Isma'il and Is-haq and Ya'qub and the tribes and 'Isa and Ayyub and Yunus and Harun and Sulaiman, and we gave Dawood the Zaboor. Prophets, some about whom we have already told you, and others about whom we have not told you. And Allah spoke to Musa directly. Prophets, givers of glad tidings and warners, so that there will be no argument for the people before Allah after (the sending of) the Prophets.] Qur'an 4/163-165
[Every time another group is thrown into it (i.e. hell) its keepers ask them: "Didn't a warner come to you?" They say: "Yes, a warner came to us and we disbelieved him saying - Allah has sent down nothing, you are in nothing but extreme delusion.] Qur'an 67/8-9
Here Allah informs us that when each group is thrown into hell, they admit that a warner had come to them, but that they denied him. This shows that no one will be cast into hell except for those who had denied the message of a warner. Allah said, speaking to Iblis:
[I will surely fill hell fire with you and those of them (i.e. people) who follow you, all together.} Qur'an 38/85
Since Allah says that He will fill hell fire with Iblis and those who follow him, we know that no one else will enter it, thus none shall enter hell fire except for those who followed shaitaan. This proves that no one who is free of sins will enter the fire, because such a person is of those who did not follow the devil, just as the previous verse proved that none will enter it except for those who have no defense for themselves after the coming of the prophets.