In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Allaah [The Exalted] said:
مِنۡ أَجۡلِ ذَٲلِكَ ڪَتَبۡنَا عَلَىٰ بَنِىٓ إِسۡرَٲٓءِيلَ أَنَّهُ ۥ مَن قَتَلَ نَفۡسَۢا بِغَيۡرِ نَفۡسٍ أَوۡ فَسَادٍ۬ فِى ٱلۡأَرۡضِ فَڪَأَنَّمَا قَتَلَ ٱلنَّاسَ جَمِيعً۬ا وَمَنۡ أَحۡيَاهَا فَڪَأَنَّمَآ أَحۡيَا ٱلنَّاسَ جَمِيعً۬اۚ وَلَقَدۡ جَآءَتۡهُمۡ رُسُلُنَا بِٱلۡبَيِّنَـٰتِ ثُمَّ إِنَّ كَثِيرً۬ا مِّنۡهُم بَعۡدَ ذَٲلِكَ فِى ٱلۡأَرۡضِ لَمُسۡرِفُونَ
Because of that We ordained for the Children of Israel that if anyone killed a person not in retaliation of murder (i.e. after given a fair trial in the courts of divine law, found guilty and capital punishment carried out by state authorities ), or to spread mischief in the land – it would be as if he killed all mankind, and if anyone saved a life, it would be as if he saved the life of all mankind. And indeed, there came to them Our Messengers with clear proofs, evidences, and signs, even then after that many of them continued to exceed the limits (e.g. by doing oppression unjustly and exceeding beyond the limits set by Allah by committing the major sins) in the land! [Surah Al-Maa’idah. Verse 32]
Recent Crime of Murder Committed by a non-Muslim Extremist: June 8th 2021
Muslim and non-Muslim extremists Updated: [Khawaarij of Somalia (Al-Shabab) Shed Blood Again [Saturday September 25th]: https://www.usnews.com/news/world/articles/2021-09-25/8-dead-as-al-shabab-claims-blast-in-somalias-capital
Muslim and Non-Muslim Extremists – [Some Individuals and Groups]