Islam and Muslims

Islam means submitting to Allaah, worshipping Him alone and
obeying Him, and shunning shirk (polytheism, associating others with Allaah)
and those who believe in that. This is the religion which Allaah approves
for His slaves. Allaah says (interpretation of the meaning): 

“Truly, the religion with Allaah is Islam”

[Aal- ‘Imraan 3:19] 

“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”

[Aal ‘Imraan 3:85]

The person who enters
this religion is called a Muslim (one who submits), because he has submitted
(aslama) to all the rulings that have come from Allaah and from the
Messenger of Allaah (peace and blessings of Allaah be upon him). Allaah
says (interpretation of the meaning): 

“And who turns away
from the religion of Ibraaheem (Abraham) (i.e. Islamic Monotheism) except
him who befools himself? Truly, We chose him in this world and verily, in
the Hereafter he will be among the righteous.

When his Lord said to
him, ‘Submit (i.e. be a Muslim)!’ He said, ‘I have submitted myself (as a
Muslim) to the Lord of the ‘Aalameen (mankind, jinn and all that exists).’”
[al-Baqarah 2:130-131] 

“Yes, but whoever
submits his face (himself) to Allaah (i.e. follows Allaah’s religion of
Islamic Monotheism) and he is a Muhsin ( a doer of  good who does good deeds
solely for the sake of Allaah) then his reward is with his Lord (Allaah), on such shall be no fear, nor shall they grieve”

[al-Baqarah 2:112].