The Holy Quran also says in Surah Maedah (5), verse 32, regarding the act of unjustly killing an innocent being and equaling it to a sin of killing entire humanity.
“…Whosoever slays a soul, unless it be for manslaughter or for mischief in the land, it is as though he slew all men; and whoever keeps it alive, it is as though it kept alive all men.”
In order to understand what Islam is, one needs to learn from those personalities who were entrusted with the responsibility of spreading the Islam and the Message of God. The Prophets, Messengers & Imams are those representatives, who were appointed by God for the guidance of mankind and the reformation of the society. The lives of these representatives of God were only aimed at establishing peace among the people and removing the curtains of ignorance which blinded man’s vision. They were always prepared to even sacrifice their own lives in order to fulfill their aim and for the sake of Islam. When we talk about sacrifice, one such great personality who instantly comes to mind is Imam Husain (a.s.).