Although Sikhi doesn't have anything to say about infidels (non-Sikhs) it does talk about slanderers and faithless cynics. I don't know if that's suitably related?
This is a very appropriate query Ishna Ji, this is a question that frequently comes to my mind.
I'll try to share as much I feel I'm confident with.
* What I feel is, wherever the adjectives of
Manmukh(ਮਨਮੁਖ), Duhaagan(ਡੁਹਾਗਣ), Saakat(ਸਾਕਤ) have been used in the Gurbani they are shown in direct contrast to the Gurmat principles, in other words, they are used as a method of poetic contrast. Most of such Shabads end with the exaltation of
Naam, Truthfulness and
Gurmat, and that is pricesly what is meant by the use of these examples/words.
* Then there are portions of the bani where Gurbani authors use the negative and lowly epithets for themselves too.
For example,
-In the Jap Ji Sahib Pauris with the refrain of ਅਸੰਖ which describe the many facets of the Creator's nature, Guru Nanak Sahib ends the Pauris with
ਕੁਦਰਤਿ ਕਵਣ ਕਹਾ ਵੀਚਾਰੁ ॥
What power have I to describe Thine doctrines (Thee)?
ਵਾਰਿਆ ਨ ਜਾਵਾ ਏਕ ਵਾਰ ॥
I cannot even once be a sacrifice unto Thee.
ਜੋ ਤੁਧੁ ਭਾਵੈ ਸਾਈ ਭਲੀ ਕਾਰ ॥
Whatever pleases Thee, is a good pursuit.
ਤੂ ਸਦਾ ਸਲਾਮਤਿ ਨਿਰੰਕਾਰ ॥੧੭॥
Thou art ever safe and sound, O Formless One!
(Guru Granth Sahib Maharaj, Page 3)
But in the Pauri which talks of thieves, ignorants and wrongdoers, Guru Sahib calls himself
Nanak the lowly
ਨਾਨਕੁ ਨੀਚੁ ਕਹੈ ਵੀਚਾਰੁ ॥
Nanak, the lowly, gives description.
ਵਾਰਿਆ ਨ ਜਾਵਾ ਏਕ ਵਾਰ ॥
I cannot even once be a sacrifice unto Thee.
ਜੋ ਤੁਧੁ ਭਾਵੈ ਸਾਈ ਭਲੀ ਕਾਰ ॥
What ever pleases Thee, that is a good pursuit.
ਤੂ ਸਦਾ ਸਲਾਮਤਿ ਨਿਰੰਕਾਰ ॥੧੮॥
Thou art ever safe and sound, O Formless One!
(Guru Granth Sahib Maharaj, Page 4)
Read this tuk by Bhagat Ravidas,
ਮੇਰੀ ਜਾਤਿ ਕਮੀਨੀ ਪਾਂਤਿ ਕਮੀਨੀ ਓਛਾ ਜਨਮੁ ਹਮਾਰਾ ॥
My social status is low, my ancestry is low, and my life is wretched.
ਤੁਮ ਸਰਨਾਗਤਿ ਰਾਜਾ ਰਾਮ ਚੰਦ ਕਹਿ ਰਵਿਦਾਸ ਚਮਾਰਾ ॥੫॥੬॥ I have come to Your Sanctuary, O Luminous Lord, my King; so says Ravi Daas, the shoemaker. ||5||6||
(Guru Granth Sahib Maharaj, Page 659)
Gurbani is composed entirely in poetry, and uses multiple figures of speech, so like any other form of poetry, the spirit of Gurbani too can only be understood only if the Shabad/Bani/Pauri is read in its entirety.
As far as I have experienced the Guru Granth Sahib and Sikhi principles, Sikhs are not encouraged or called to look down upon other faith traditions or 'non-believers', instead Sikhism advocates a free discourse. The heterogeneity of Gurbani authors is a shining example of that.