Islam is the religion that Allah sent to Muhammad (sallallaahu alaihi wa-sallam) and made it the final and most complete religion for His slaves. Allah perfected, in this religion, the bounties that He bestowed on His salves, and accepts only Islam from them. He said, what translated means: “Muhammad (sallallaahu alaihi wa-sallam) is not the father of any man among you, but he is the Messenger of Allah, and the Last (end) of the Prophets.” [33:40], “This day, I have perfected your religion for you, completed My favor upon you, and have chosen Islam for you as your religion.” [5:3], “Truly, the religion with Allah is Islam.” [3:19] and, “And whoever seeks a religion other than Islam, it will never be accepted of him, and in the Hereafter he will be one of the losers” [3:85]
Allah obligated all mankind to follow Islam:
“Say (O Muhammad (sallallaahu alaihi wa-sallam): “O mankind! Verily, I am sent to you all as the Messenger of Allah, to Whom belongs the dominion of the heavens and the earth. There is none who has the right to be worshipped but He; It is He Who gives life and causes death. So believe in Allah and His Messenger (Muhammad (sallallaahu alaihi wa-sallam), the Prophet who can neither read nor write, who believes in Allah and His Words (this Qur’aan, the Torah and the Gospel), and follow him so that you may be guided” [7:158]. Abu Hurayrah (radhi allahu anhu) reported that the Messenger of Allah (sallallaahu alaihi wa-sallam) said, what translated means, “By Whom the soul of Muhammad is in His Hand! No member of this nation, no Jew or Christian, hears of me and does not believe in what I was sent with, but he will be of the people of the Fire.” [Saheeh Muslim]
Believing in the Messenger means believing in what was revealed to him, coupled with acceptance and submission; without them the belief is not sufficient. This is why Abu Talib, the Prophet’s (sallallaahu alaihi wa-sallam) uncle, was not a believer in the Messenger, although he believed in what he was sent with and confirmed that Islam was the best religion, (but without acceptance or adherence to Islam).
Islam contains all of what brings benefit, which was also contained, in previous religions. Islam, however, is suitable for implementation anytime, anywhere and by any nation. Allah said to His Messenger (sallallaahu alaihi wa-sallam), what translated means, “And We have sent down to you (O Muhammad (sallallaahu alaihi wa-sallam)) the Book (this Qur’aan) in truth, confirming the Scripture that came before it and dominant over it” [5:48]. The meaning of “suitable for implementation at anytime, anywhere and by any nation,” is that Islam brings only benefit to mankind, whenever and wherever it is implemented. Islam is not under the control, and thus is not to be altered by, any nation living at any given time at any given place, as some people would want it to be.
Islam is the religion of truth. It is the religion that Allah guaranteed aid and dominance for whoever firmly adheres by it. He said, what translated means, “It is He who has sent His Messenger (Muhammad (sallallaahu alaihi wa-sallam) with guidance and the Religion of Truth (Islam), to make it superior over all religions even though the disbelievers hate it.” [9:33] and, “Allah has promised those among you who believe, and do righteous, good deeds, that He will certainly grant them succession to (the present rulers) in the earth, as He granted it to those before them, and that He will grant them the authority to practice their religion, which He has chosen for them (Islam). And He will surely give them in exchange a safe security after their fear (provided) they (the believers) worship Me and do not associate anything (in worship) with Me. But whoever disbelieved after this, they are the rebellious (disobedient to Allah).” [24:55].
Islam contains belief and Law: It is a complete religion, both in its belief and in its Law. It demands from its followers the following:
1 Believing in Taw’hid (Oneness) of Allah and disbelieving in Shirk (polytheism).
2. Being truthful and not lying.
3. Being just, that is to deal comparable things with equality, and abandoning injustice.
4. Being honest and abandoning treachery.
5. Preserving one’s promises and contracts and not breaking them.
6. Being dutifully good to one’s parents and not cutting ties of kinship.
7. Keeping relations with relatives and not cutting them.
8. Being good with neighbors and not harming them.
In general, Islam orders Muslims to have the best possible conduct and forbids all bad behavior. It requires Muslims to enjoin every righteous deed and avoid every evil deed. Allah said, what translated means, “Verily, Allah enjoins justice, Al-I’hsan (excellence in religion), giving (help) to kith and kin, and forbids all evil (deeds), Al-Munkar (all that is prohibited) and injustice. He admonishes you, that you may take head)’ [16:90]
[By Sheikh Muhammed Sahih Ibn al-Uthaimeen|Translated into English by: Dr. Saleh As-Saleh]