Regarding the fact that ‘Salam’ and ‘Islam’ denote the Holy Imams and their Shias
There are some verses on this topic:
يَا أَيُّهَا الَّذِينَ آمَنُوا ادْخُلُوا فِي السِّلْمِ كَافَّةً وَلَا تَتَّبِعُوا خُطُوَاتِ الشَّيْطَانِ إِنَّهُ لَكُمْ عَدُوٌّ مُبِينٌ.
O you who believe! Enter into submission one and all and do not follow the footsteps of Shaitan, surely he is your open enemy. (Surah Baqarah 2:208)
Ayyashi with many chains has related that submission refers to the Wilayat of Ali (a.s.) and after him the Wilayat of his vicegerents and accepting their Imamate and recognition (Ma’refat) and the ‘footsteps of Shaitan’ refers to the Wilayat of the unjust Caliphs.1
ضَرَبَ اللَّهُ مَثَلًا رَجُلًا فِيهِ شُرَكَاءُ مُتَشَاكِسُونَ وَرَجُلًا سَلَمًا لِرَجُلٍ هَلْ يَسْتَوِيَانِ مَثَلًا الْحَمْدُ لِلَّهِ بَلْ أَكْثَرُهُمْ لَا يَعْلَمُونَ.
Allah sets forth an example: There is a slave in whom are (several) partners differing with one another, and there is another slave wholly owned by one man. Are the two alike in condition? (All) praise is due to Allah. Nay! Most of them do not know. (Surah Zumar 39:29)
Most commentators have said that this example is for the polytheists and the monotheists. The polytheist is like a slave having many masters and all of them are opposed to each other. Each of them issues a different order and each puts the needs of the slave on the other person. This is the condition of a polytheist, if they had intellect and had understood worship, they would have realized all the work performed by them is useless.
While the monotheist, who is the slave of only one Allah and worships only one Allah Who is generous, merciful and has all the powers, and Who has the powers to give profit and loss. Indeed this would be better than the one who worships many gods and none from them pays heed.
Kulaini in Kafi and Maniul Akhbar has narrated that Allah has mentioned this example for the enemies of Amirul Momineen (a.s.). There are two reason for this: The first reason is: ‘There is a slave in whom are (several) partners’ is the first unjust one, all of whose followers are following different ways, because their Imam is not on the right that is why there are different sects among them and: ‘slave wholly owned by one man’ are the followers of Amirul Momineen (a.s.) because their Imam is on the right. And his knowledge is from Allah, that is why all his followers are on one path.
The other reason is that the first one and people like him who apparently follow the Holy Prophet (S) but actually they follow Satan and their own misguidance. And the second one is Amirul Momineen (a.s.) who followed the Messenger of Allah in all the affairs. Thus Abul Qasim Haskani has narrated that Amirul Momineen (a.s.) said: I am that man who with the Messenger of Allah in every matter. In another tradition he says that, ‘Muslim’ is one of my names in the Quran.
وَإِنْ جَنَحُوا لِلسَّلْمِ فَاجْنَحْ لَهَا وَتَوَكَّلْ عَلَى اللَّهِ إِنَّهُ هُوَ السَّمِيعُ الْعَلِيمُ.
And if they incline to peace, then incline to it and trust in Allah, surely He is the Hearing, the Knowing. (Surah Anfal 8:61)
Commentators have said that this verse is has been abrogated by the verse of ‘killing’ or that it specially with regard to the People of the Book as Jizya can be accepted from them.
Kulaini has narrated through reliable chains from Imam Sadiq (a.s.) that ‘Peace’ denotes entering our affair, that is accepting our Imamate.2