I am the queen of late replies, so it's ok, jio.
I was of the understanding Sikhi is panentheistic, rather than monotheistic. Gurbani describes the Ik Onkar as something less personalised than a monotheistic God-character (that is, a God entity with a personality who speaks in the first person).
"Paap", and in fact the word "sin" itself, may be better translated as "mistake". The word "sin" as used in Abrahamic faiths at least, seems to carry more weight than a mistake. When an Abrahamic follower sins, they have transgressed against God, and must seek forgiveness. Forgiveness of sins, confessing of sins, deadly sins, etc. In Sikhi, there isn't such an emphasis.
Can you tell me which things in Sikhi are against the divine God, or that you would classify as a sin against Guruji?
I think this tuk from the shalok of Japji Sahib sums up Sikhi's position best:
Good deeds and bad deeds-the record is read out in the Presence of the Lord of Dharma.
According to their own actions, some are drawn closer, and some are driven farther away.
Sikhs don't make mistakes by transgressing God's laws (I'm not even sure what laws have been laid down in Sikhi). Sikhs make mistakes by being tangled up with ego-maya and failing to recognise the Sat that is eternal. This is the be-all and end-all.