The previous ayat clearly show from the Qur'an that the Muslims must be one Ummah, one brotherhood, one community of believers. They should never fall into disputes amongst each other. This is why it is obligatory on the Muslims to establish a Khilafah, or a united Islamic state, ruled by the Islamic Shariah.

There are also proofs from the Hadith that Muslims must establish Khilafah:

As for the Sunnah, Nafi'a reported saying: “'Umar said to me that he heard the Prophet (Salallahu Alaihi Wasalaam) saying: Whoso takes off his hand from allegiance to Allah (Subhaanahu Wa Ta'Ala) will meet Him (Subhaanahu Wa Ta'Ala) on the Day of Resurrection without having any proof for him, and whoso dies whilst there was no bay'ah (allegiance or a pledge) on his neck (to a Khaleefah), he dies a death of jahilliyah.”

This is because the state of the people during the jahiliyah and before Islam was that they were divided with no single leader. They were constantly fighting amongst themselves wasting their efforts and resources. After Islam came, it united them into a single Ummah and a single community of believers with one leader. So whoever chooses not to participate in this new united community has reverted to the state of the pre-Islamic jahiliyah.

Also, the following hadith serves as a warning as to how dangerous it is to be divided into groups with more than one leader. It also proves that the Muslims must always have only one leader:

As narrated by 'Arfajah that he heard the Messenger of Allah (Salallahu Alaihi Wasalaam) say, “If someone comes to you when you are united over one man and wants to break your strength and divide your unity, kill him.”

After reading the previous ayat and ahadith, some people may say: There is no longer an Islamic nation, and there is no Khaleefah today to give bay'ah or allegiance to, so what can we do?

The answer to this is clear. The previous ayat and ahadith give us an image of what the state of the Muslims should be. Therefore, if an Islamic state existed we must protect it at all cost. However if no Islamic state exists, such as our situation today, this does not excuse us from not following these ayat and ahadith.

We must work to re-establish Khilafah and appoint our best person to be a Khaleefah, giving him our allegiance and pledge to follow him as long as he does not go against the Qur'an or the Sunnah.