Quran

They exchanged that for (a small price), worthless vanities of the world, which are their desires and whims that they followed. This verse explains the preceding one, (and most of them are defiantly disobedient), whoever follows his whims and lustful desires, will become defiantly disobedient. Al-Alusi: 5/251.
Question: In light of this verse, describe the risk of following whims on the Muslim's faith.

The reason why they are described as hostile toward you and as hating you is the issue of faith, so defend your faith and support it; take those who oppose it as your enemies and take those who support it as your allies and friends, basing your relationships with others on that criteria; do not base the issue of friendship or enmity on personal inclinations, whims and desires, and do not follow the soul that prompts one to evil with regard to this matter. Al-Saadi: 330.
Question: What is the wisdom behind focusing on the "belief" in (toward a believer)? What lesson should be learned from this for a Muslim?

Brotherhood in Islam is conditional upon repentance from shirk, establishing prayer, and giving zakah. If these conditions are not met, then a person cannot be considered a brother in Islam. Ibn Taimyah: 3/311
Question: Can a person, who does not pray, be considered a brother in Islam?

(If they repent), repent from shirk, (establish prayer and give zakah, then they are your brothers), indeed, they become your brothers (in religion), they have the same rights as yours, and carry out the same duties as you do. Al-Baghawi: 2/253.
Question: What are the foundations by which brotherhood is realized among the believers?

Reviling is ascribing inappropriate things to the religion, or objecting, in an irreverential manner, to a religious ruling that is definite and supported by a clear evidence. Al-Qurtubi: 10/123.
Question: What is reviling the religion?

They are singled out for mention because of the seriousness of their offence, and because others follow them. This also highlights the fact that whoever reviles Islam and takes it upon himself to oppose it, is one of the leaders of disbelief. Al-Saadi: 330.
Question: The leaders of disbelief are singled out for mention. Why?

The condition clause, (if you are truly believers) is used in this verse -even though it is certain- in order to stimulate their religious devotion, so they would prove that they are true believers who fear Allah, not the people. Ibn Ashur: 10/134.
Question: The condition clause: (if you are truly believers) is used in this verse. Why?