Gur-mat is the name for the eternal (not human) Guru’s wisdom. No other school of wisdom other than Gurmat has the potential to reach the truth. That is why various such schools, which enslave people into the web of illusion have been collectively termed as Manmat. On the other hand, the proponents of these Manmat schools have tagged the true seekers of the truth as atheists (or Naastik, ill-guided etc). The preachers of such Manmat schools consider those people as theists who agree with their philosophy, while those who disagree have been equated to atheists.
Theists (Aastik) and Atheists (Naastik) are antonyms according to the Brahminical school of thought. Consequently, all those who displayed disagreement with the philosophy of the Brahmin and disproved the falsehood within Shastras through logical arguments were defamed by naming them as atheists. On the contrary, Gurmat, which has the potential to bring truth into light, considers both of these words (theist and atheist) to be on a similar standing. That is because, neither of these words have any relation to the truth. Thus, two newer words, Gurmukh and Manmukh were carved to exhibit the sentiment behind the previous two words. Gurmukh are considered those who are in union with the Guru, while the word Manmukh is used to represent both the sets of people for whom Brahmin has used theist and atheist. While a Manmukh lives life according to the wishes of his mind, aGurmukh lives life according to the will of his Satgur (i.e. his inner voice).
According to Gurmat, Satgur is inside every person and no one is bereft of Satgur,
ਸਤਿਗੁਰ ਤੇ ਖਾਲੀ ਕੋ ਨਹੀ ਮੇਰੈ ਪ੍ਰਭਿ ਮੇਲਿ ਮਿਲਾਏ ॥
Satgur te khaali ko nahi mere prabh mel milaye|| (Page 850)
But until the time one is capable to attune to one’s Satgur (or the inner voice), one has to gain understanding through the word of the Guru (or Gurbani). Therefore, in the initial stageGurbani acts as the eternal command for us. Living life according to this command, one can get attuned directly to the eternal Guru from within oneself.
The words Gurmukh and Manmukh have appeared at various places in Gurbani. Theist (Aastik) and Atheist (Naastik) are used rarely and wherever they have been, carry interchangeable meanings, for instance,
ਆਸਤਿ ਨਾਸਤਿ ਏਕੋ ਨਾਉ ॥
Aasti Naasti Eko Naao || (Page 953)
In the Brahminical school of thought, Aasti (theist) has been referred to someone who has blind faith on this school. But in reality, a school of thought that has nurtured greed in its followers and whose proclaimed target has been self-aggrandizement can only be equated to Naasti (or Naashvant, i.e. mortal). That is why according to Gurmat, both these words,Aasti and Naasti are synonyms.
The language (not to be confused with script) of Gurbani (i.e. Gurmukhi) is different from worldly languages. Many words that appear in Gurbani (Aad Granth) have come from various other schools of thought, but they have been given newer meanings (based onGurmat) and those meanings are explained in Gurbani itself. Gurbani has redefined many words from the Hindu schools of thought, for example Swarga (Heaven), Punn-Paap (Virtue-Sin), Jamman-Maran (Birth-death), Brahm, four Eons/Yugs, and four Padarath(Substances) etc. Here we will talk about only one of them, for instance: Swarga (Heaven) is conceived to be a place somewhere in the sky according to the Hindu school of thought. If one were to look at the etymology for this word, Swa+Ghar = Own+House. In order to maintain the distinction of the newer meaning and to keep it safe from confusions, Gurmatuses Nij instead of Swa which also means ‘own’, hence the word Nij+Ghar (also calledHirda). Each person’s Nij+ghar is in his inside, while Swarga is believed to be somewhere in the sky. There are relevant references in Gurbani that testify to this fact, such as the following
ਸਭਿ ਸਖੀਆ ਪੰਚੇ ਮਿਲੇ ਗੁਰਮੁਖਿ ਨਿਜ ਘਰਿ ਵਾਸੁ ॥
ਸਬਦੁ ਖੋਜਿ ਇਹੁ ਘਰੁ ਲਹੈ ਨਾਨਕੁ ਤਾ ਕਾ ਦਾਸੁ ॥੧॥
Sab sakhiya panche mile Gurmukh nij ghar vaas ||
Sabad khoj eh ghar lahe nanak ta ka daas || (Page 1291)
ਸਭ ਕਿਛੁ ਘਰ ਮਹਿ ਬਾਹਰਿ ਨਾਹੀ ॥
ਬਾਹਰਿ ਟੋਲੈ ਸੋ ਭਰਮਿ ਭੁਲਾਹੀ ॥
ਗੁਰ ਪਰਸਾਦੀ ਜਿਨੀ ਅੰਤਰਿ ਪਾਇਆ
ਸੋ ਅੰਤਰਿ ਬਾਹਰਿ ਸੁਹੇਲਾ ਜੀਉ ॥
Sabh kichh ghar meh baahar naahi ||
Baahar tolai so bharam bhulahi ||
Gur parsaadi jinni antar payeya ||
So antar baahar suhela jeeo || (Page 102)