do you take hadith ?
Bukhari, volume 9, #17
"Narrated Abdullah: Allah's Messenger said, "The blood of a Muslim who confesses that none has the right to be worshipped but Allah and that I am His Messenger, cannot be shed except in three cases: in Qisas (equality in punishment) for murder, a married person who commits illegal sexual intercourse and the one who reverts from Islam (Apostate) and leaves the Muslims."
one could argue with Qisas.. but the others you can't really argue (small example)
Response: The other two can very much be argued and are justified. The hadith itself clearly states that blood "can be" shed, not that blood "should be" shed. That alone demonstrates, that death is not obligatory simply because they revert from islam or have sex outside of marriage. The words acknowledge that there are conditions, supported by the Qur'an and several other hadiths.
Concerning Apostasy, it is when one who leaves islam becomes violent against muslims or simply embraced islam, only as a strategy of war to destroy muslims from within and utilize their knowledge of muslims against them in war once they leave islam. In this case, it is self-defense, therefore, the killing of the apostate is justified.
Concerning adultery, the death penalty was prescribed in the torah, not in islam. So it was accustomed by Muhammad (saw) to follow the Torah untill Allah(swt) revealed differently. As any reasonable person will recognize, having sex out of lust is severely, emotionally, devastating, act. Why else does a person feel so devastated after being molested or cheated on? It is because the sexual experience was not an act of love, but one out of lust. As a result, a severe punishment is necessary to prevent sexual activity based on lust, and not out of love. Thus the hadith is justified.