Walaikum salaam sister,
The Quran does not instruct believers to follow the 'religion' (deen) of Abraham. This concept is commonly misunderstood by many traditional Muslims too. The
'deen' for believers is prescribed by the Quran (with specific laws) and remains complete (6:114).
The Quran instructs believers to follow the
'millat' of Abraham. This is rather different from 'deen' (religion). The two terms have different meanings. This is also supported with verses such as 6:161 which discriminate between the two terms.
The term 'millat' has been explained by Quran itself through numerous verses which refer to monotheism as opposed to idolatry (e.g. 16:123; 3:95; 6:161), or a set of beliefs / creed of a particular people (2:120). Some millat's can also be false and do not lead aright.
For example, Muslims may fall under the same canopy of 'Islam', but different sects within it may follow different 'millats' (beliefs / creeds etc) which may not all be congruent with the overarching true essence of the Islam. This is also true of Judaism and Christianity.
Furthermore, Islam is an encompassing religion which was revealed to all Prophets. However, it included different
'laws' (shariah) prescribed to different communities. We note this in the following verse where albeit one 'religion' was prescribed to all Prophets and their communities (42:13), laws (shariah) within them differed.
005:048 (part)"... To each among you have we prescribed a law (Arabic: Shari-atan) and an open way (Arabic: wamin-hajan)..."We also note different 'millats' (creeds) of different followers of the scriptures. Believers are told
explicitly not to follow their 'millats'.
002:120"Never will the Jews or the Christians be satisfied with you unless you follow their form of religion / creed (Arabic: Millatahum). Say: "The Guidance of God, that is the (only) Guidance." Were you to follow their desires after the knowledge which has reached thee, then you would find neither Protector nor helper from God"
We further note in the Quran a reference to Prophet Abraham's good example (Us'watun Hasanatun - 60:4) which is to be emulated. From verse 60:4 it is clear that this is a reference to:
(i) Belief in God alone.
(ii) No worship to any other than to God.
(iii) Complete reliance in God and firm belief in the Last Day.
Therefore, what we are asked to follow is Prophet Abraham's 'millat' (refraining from idolatry and adherence to his creed / certain set of beliefs commensurate with monotheism) not 'religion' (deen).
Certain aspects of Prophet Abraham's practices that he enjoined on his communities and are imposed on believers are clearly expounded by the Quran (a Book fully detailed - 6:114) such as prayer, zakat etc.
There is absolutely no prescription for circumcision in the Quran for believers. The Quran remains a complete guide (huda) explained in detail (41:3; 11:1, 12:111 - tafsila), an explanation of all things necessary for religion (tibiana lekulli shayin 16:89), a criterion to judge between right and wrong (furqan 25:1) and the only source for religious guidance (6:114)
My article on circumcision below may help further, God willing.
CIRCUMCISIONhttp://quransmessage.com/articles/circumcision%20FM3.htmI hope this helps.
Joseph