Satgyan-pujari

Firstly there can never be any justification in deleting/changing historical texts,any different viewpoint should only be put in footnotes and backed up with evidence if available.It is not in the Panthic benefit to have texts changed by modern sikhs/singh sabha or british,to view from a biased viewpoint.If the sanatan/camp where to use these tactics modernist/singh sabha would be in uproar crying foulplay.there is no reason or honesty in blatant deletion and additions according to personal viewpoint.

As Xylitol said, its sharda plain and simple. However there is very fine line difference between sharda and dangerous dvaish/dvait mindset which many sikhs have fell, Here is an example of that fine line difference:

Example of sharda:

In one's mind there is full faith towards sri guru nanak dev ji eg- baba nand singh ji maharaj. However, one does not feel need to prove that sharda by debating/discussing/comparing their own ishatdev with others ishatdev. In those minds, there is no dvaish(partiality) or dubta or dvait(duality), all is god, god is all- seeing their ishatdev in everything/everyone.

Example of people diseased with dangerous mindset of my prophet is better than yours:

Completely overlooking at the tat gyan of all the dharams, in ignorance/false pride(jhota ahankar) claiming my prophet is better than yours by comparing avtars life, taking prophets words /gurbani out of context. Usually shariapanthis feel that in order to have full sharda of their own ishatdev they must put down other prophets by comparing them. Gurbani teaches, avtars are sargun form of vahiguroo, are here for certain task to benefit human kind, i just dont understand how others generally speaking can do nindya of other avtars by comparing, you cannot compare them because they all coming from the same source- Nirgun Vahiguroo, if avtars are given different duties how can you compare them, that itself shows people who compare live in dubta and live in dvait which is opposite of gurmat advait marg.

I have revisited this topic, and find it extremely helpful and thought provoking.
The question that tsingh provided in his post "Who is your Guru" is I agree a pivotal one, for anyone following Sikhism. Of the two positions regarding Guru Maharaj as "Sargun Wahiguru" as opposed to "Prophet/Perfect Saint", I personally fall into the first category. 
Of the Vaars as expounded by Bhai Gurdas Ji, which primarily confirm the traditional view of the continuity and manifestation of Guru Maharaj as Sargun swarup Wahiguru, I find Vaar1 pauries 23/24 challenging my understanding of this fact. These pauries appear to indicate that Guru Nanak was sent by God and was blessed to teach the Truth of Naam and Bhakti to suffering humanity, after intense devotion and tapasya. 
Could the learned members on this forum please put these pauries in the context of Guru being God himself, and remove any doubts to the traditional understanding 
Vaar1 p23 
ਸੁਣੀ ਪੁਕਾਰਿ ਦਾਤਾਰ ਪ੍ਰਭੁ ਗੁਰੁ ਨਾਨਕ ਜਗ ਮਾਹਿ ਪਠਾਇਆ
The benefactor Lord listened to the cries (of humanity) and sent Guru Nanak to this world
ਚਰਨ ਧੋਇ ਰਹਰਾਸਿ ਕਰਿ ਚਰਣਾਮ੍ਰਿਤੁ ਸਿਖਾਂ ਪੀਲਾਇਆ।
He washed His feet, eulogised God and got his Disciples drink the ambrosia of his feet.
 
Vaar1 p24
ਪਹਿਲਾ ਬਾਬੇ ਪਾਯਾ ਬਖਸੁ ਦਰਿ ਪਿਛੋ ਦੇ ਫਿਰਿ ਘਾਲਿ ਕਮਾਈ।
First of all Baba Nanak obtained the gate of the grace (of Lord) and then He underwent and earned the rigorous discipline( of heart and mind).
ਰੇਤੁ ਅਕੁ ਆਹਾਰੁ ਕਰਿ ਰੋੜਾ ਕੀ ਗੁਰ ਕਰੀ ਵਿਛਾਈ।
He fed himself with sand and swallow-wort and made stones his bedding i.e. he enjoyed poverty too.
ਭਾਰੀ ਕਰੀ ਤਪਸਿਆ ਵਡੇ ਭਾਗੁ ਹਰਿ ਸਿਉ ਬਣਿ ਆਈ।
He offered his full devotion and then he was fortunate to have proximity with God.
ਬਾਬਾ ਪੈਧਾ ਸਚਖੰਡਿ ਨਉ ਨਿਧਿ ਨਾਮੁ ਗਰੀਬੀ ਪਾਈ
Baba reached the region of truth wherefrom he received Nam, the storehouse of nine treasures and humility.
 
 

The only problem is, if you give yourself only four options you'll find that to be your answer. That explanation you give above is clearly the answer Bahadaur Ali Shah has come to. There are numerous angles on this, not four. So for some nirmalay i've met they fall somewhere between two and a wee bit of four but in a more sophisticated manner than the positions above. Truth always existed, but the means to truth is shaped according to the context (yug dharma). Hence you can have continuity with prior yugas (as Bhai Gurdas certainly maintains in his explanation of waheguru mantr and Guru Arjun Dev Ji including the shabads of the bhats), yet in kalyug the most appropriate expression of yugdharma being gurmat. The implications of that are applicable to all traditions within kalyug...to varying degrees. Now, the danger of number four as you've presented it there is that Sikhi becomes very little (my value judgement of course) other than an appeal to reconsider the parent-tradition your born into in a new light. If that were entirely true you wouldn't anticipate there being philosophical, psychological, phenomenological consistency in the Guru's teachings...since it should actively avoid making hard and fast positions that might conflict with prior revealed tradition. It should simply express the truth as such in the most simplistic of terms without allowing for doctrinal demarkations. This is where this fourth theory falls apart. The samprdais have written masses of literature highlighting the consistency of gurmat updesh, thoroughly enlarging on the language of the Gurus and the sidhant (reasoned philosophical conclusions) it is based upon. Even James Massey's preliminary analysis of the language of Gurmat shows its to be largely based upon vaishnav terms for Parmatma (100s) and shaastra based terminlogy, compared to Islamic (maybe three islamic terms used for God?). Prior to that you have Bhai Gurdas Ji in his kabit svayay placing gurmat as the perfect darsana after having talked of the earlier schools of philosophy. He doesn't mention any continuity with Islamic schools of thought. Take for example Sidh Gosht. It is incredibly specific on certain philosophical and doctrinal angles. Is this a matt open to all monotheistic hindus and muslims? Clearly not sarguni vaishnavs for a start, or any muslim who doesn't accept the centrality of advaita nirgun mukti, the four fold division of consciousness, the role of karam, the emphasis on hari avtara, etc. This is as specific a matt as any other in India at that time. Guru Maharaj corrects the Naths, and provides specific adhyatmic clarification of their deliberately ambiguous metaphors. Specifically while grihasth dharma has highlighted chaar purushaarths, sikhi is primarily mokshartha alike vedanta in that sense. Alike vedanta, morality is defined in relation to that goal, through the pratically oriented yams and niyams. To conclude from that that Sikhi as it stands is not an autonomous tradition as such since it lacks formal codes of moral conduct, is to fundamentally fail to recognise what Sikhi is and to chain it to an semitic understanding of how a religion should work (turning it into a house of heresy that should be burned to the ground from what i hear!). How that worked practically is that like all traditions that existed in india at that time it worked at a level in which everyone could take something from it...but within that there were hierarchies of commitment to the specific nuances of Gurmat. We have bhagat jaidev and bhagat surdas shabads, yet those of their traditions would fundamentally disagree with the sidhant of gurmat. To my mind thats what we're talking about...and of course there are further opinions i've come across.