Here is the view of the Salaf and the Scholars of Islam on Apostates:

People make a lot of fuss about this, the orthodox view of Sunni Islam is that the Murtad (Apostate) is to be killed if he does not repent within the given time by the government. This is the consensus of the scholars of Ahlus Sunnah Wal-Jama'ah AKA Sunni Islam, and every Islamic Scholar before the 21st century would tell you the same. It's only the 'modern' Muslims thinking they know everything about Islamic Law trying to change the idea.

The truth is that all four schools of thought have that opinion, and almost every single Sunni scholar from any background said the same. No one tried questioned the idea until recently.

The evidence for it is sealed with it Ijmaa' (consensus) among all 4 madhabs and all the scholars of Ahlus Sunnah Wal Jamaa'ah that the Murtad (Apostate) must be punished with the death penalty. And it is the Ijmaa' (consensus) of the Sahaba (Companions) and the Tabie'een (Followers of the companions) as well, and there are 7-8 Sahih (authentic) routes showing the Prophet or the Sahaba (companions) ordering the punishment or punishing a Murtad (Apostate). Scholars have added the numerous Sanads (reports) and some said that the punishment is a Hadd and that it has elements of Tawatur.

This is all sealed off by the fact that Ahlus-Sunnah made a united statement in all their books and it goes as follows:

«وأجمع أهل العلم على وجوب قتل المرتد. وروي ذلك عن أبي بكر، وعمر وعثمان، وعلي، ومعاذ، وأبي موسى، وابن عباس، وخالد، وغيرهم، ولم ينكر ذلك، فكان إجماعا ومن ارتد عن الإسلام من الرجال والنساء، وكان بالغا عاقلا: دعي إليه ثلاثة أيام، وضيق عليه، فإن رجع، وإلا قتل.»

The translation:

The consensus of the people of knowledge is that it is required to kill the Apostate and it is confirmed in reports that Abu Bakr, Umar, Uhtman, Ali, Mu'aath, Abu Moosa, Ibn Abbaas, Khalid Ibn Walid, and many more did the same, and there is no denying they did so. So it is a consensus that whoever leaves Islam, male or woman as long as he was Sane and reached Puberty, he will be called to repent for 3 days, and if he refuses, he is to be killed.

Sheikh Ul-Islam Ibn Taymiyyah said in As-Sarim al-Maslool 'ala Shatim ar-Rasool - 3/696

على خصوصها وكلاهما قد قام الدليل على وجوب قتل صاحبها والادلة الدالة على سقوط القتل بالتوبة لا تعم القسمين بل انما تدل على القسم الاول كما يظهر لمن ذلك تامل الادلة على قبول توبة المرتد فيبقى القسم الثاني وقد قام الدليل على وجوب قتل صاحبه ولم يات نص ولا اجماع بسقوط القتل عنه والقياس متعذر مع وجود الفرق الجلي فانقطع الالحاق والذي يحقق هذه الطريقة انه لم يات في كتاب ولا سنة ولا اجماع ان كل من ارتد باي قول او اي فعل كان فانه يسقط عنه القتل اذا تاب بعد القدرة عليه بل الكتاب والسنة والاجماع قد فرق بين انواع المرتدين كما سنذكره شیخ الإسلام ابن تيمية رحمه الله - الصارم المسلول على شاتم الرسول، الجزء ٣، صفحة ٦٩٦

"Apostasy is of two types: ordinary apostasy and extreme apostasy, the latter for which execution is prescribed no matter what. In both cases there is evidence that it is obligatory to execute the apostate, but the evidence indicating that the sentence of death may be waived if the person repents does not apply to both types of apostasy. Instead, the evidence indicates that that is allowed only in the first case (ordinary apostasy) as will be clear to anyone who studies the evidence that speaks about accepting the repentance of the apostate. In the second type (extreme apostasy) the obligation to put the apostate to death still stands, and there is no text nor consensus to indicate that the death sentence may be waived even if he repents."