The Era of Abraham:

Abraham, who earned the title of the friend of God, was chosen to be the leader and guide of humanity as well as the progenitor of the late prophets.

 (Al-Nisa: 125)

Who is better in religion than he who surrendereth his purpose to Allah while doing good (to men) and followeth the tradition of Abraham, the upright? Allah (Himself) chose Abraham for friend.

(Al-Baqarah: 124)

And (remember) when his Lord tried Abraham with (His) commands, and he fulfilled them, He said: Lo! I have appointed thee a leader for mankind. (Abraham) said: And of my offspring (will there be leaders)? He said: My covenant includeth not wrong-doers.

Describing the exalted position to which Abraham was raised and made a model in religion and piety for all the Unitarians, the Quran asks the faithful to follow is lead.

(An-Nahl: 120-123)

Lo! Abraham was a nation obedient to Allah, by nature upright, and he was not of the idolaters;

Thankful for His bounties; He chose him and He guided him unto a straight path.

And We gave him good in the world, and in the Hereafter he is among the righteous.

And afterward We inspired thee (Muhammad, saying): Follow the religion of Abraham, as one by nature upright. He was not of the idolaters.

 Ever since the Truth was revealed to Abraham, he continues to be the leader of mankind, and shall continue to be so till the Day of Judgement. The last prophet sent to mankind during the era of Abraham was Muhammad, and the people raised to hold the banner of Abraham aloft are the Muslims. The holy Quran makes it clear in unambiguous terms :

( Al-Hajj: 78)

And strive for Allah with the endeavour which is His right. He hath chosen you and hath not laid upon you in religion any hardship; the faith of your father Abraham . He hath named you Muslims of old time and in this (Scripture), that the messenger may be a witness against you, and that ye may be witnesses against mankind. So establish worship, pay the poor-due, and hold fast to Allah. He is your Protecting friend. A blessed Patron and a blessed Helper!

The distinguishing feature of the leadership of Abraham and his call consists of the Unity of Godhead, unalloyed and free from all traces of paganism, animism, pantheism and dualism. It rejects even the slightest trace of polytheistic cult as unsanctioned and graceless. And then Abraham beseeched God for his progeny in these words: 

(Ibrahim: 35)

And when Abraham said: My Lord! Make safe this territory, and preserve me and my sons from serving idols.