I do believe Gurbani gives us unmistakable guidance. There is no need for sitting on the fence by giving the benefit of the doubt to the occult (unseen, unknown, hidden and dark).
True that the Sikh Rehat Maryada does not contain any specific prohibitions about what we should believe about the occult. However it does not have to. The maryada is, like any maryada, a guide for living. Sri Guru Granth Sahib Ji is there to guide our beliefs. Gurbani and the maryada are not in conflict. Why not? Because the maryada does prohibit rituals that came about as a way to please, gain favor with, even control the so-called powers of the occult. That is why, for example visiting graves, is specifically mentioned along with many other practices that link back to unseen, unknown, hidden, dark, occult forces.
Where do ideas of the occult (unseen, hidden) arise? From fear of what we do not understand. Think of all manner of events for which there were no explanations and still there are none. The human mind invents explanations, and these take the form of bhoots, prets, planetary forces, the power of numbers, etc. And our fears can become so strong that they become obsessions (rituals of the mind). They also become compulsions (rituals of behavior) that take energy and weigh us down. Obsessions and compulsions -- intended to allay fear -- but have the exact opposite effect. Our minds become cluttered with them.
These are entanglements, attachments no less! They take up space, energy, thought and emotion which weigh down our ability to attach to the Merchant and the merchandise of the truth. These darken the mind and obstruct the light. They are concoctions of munn. They are passed from generation to generation. It seems we cannot free ourselves from the past.
A house cannot be both dirty and clean. So we can take a look. In blue are my reactions to some of the tuks. The translation is by Dr Sant Singh Khalsa; we can go back later and fine-tune the translation. The message is clear. From Sri raag, Ang 57
ਗੁਰ ਤੇ ਨਿਰਮਲੁ ਜਾਣੀਐ ਨਿਰਮਲ ਦੇਹ ਸਰੀਰੁ ॥
Gur ṯe nirmal jāṇī▫ai nirmal ḏeh sarīr.
Through the Guru, the Pure One is known, and the human body becomes pure as well.
ਨਿਰਮਲੁ ਸਾਚੋ ਮਨਿ ਵਸੈ ਸੋ ਜਾਣੈ ਅਭ ਪੀਰ ॥
Nirmal sācẖo man vasai so jāṇai abẖ pīr.
The Pure, True Lord abides within the mind; He knows the pain of our hearts.
Can we have the steadiness of attention to understand this if we are soothing our fears with beliefs in the occult?
ਸਹਜੈ ਤੇ ਸੁਖੁ ਅਗਲੋ ਨਾ ਲਾਗੈ ਜਮ ਤੀਰੁ ॥੧॥
Sahjai ṯe sukẖ aglo nā lāgai jam ṯīr. ||1||
With intuitive ease, a great peace is found, and the arrow of death shall not strike you. ||1||
How much peace can we expect to have when creatures coming from the darkest recesses of the human mind compete for attention in our minds with the pure One?
ਭਾਈ ਰੇ ਮੈਲੁ ਨਾਹੀ ਨਿਰਮਲ ਜਲਿ ਨਾਇ ॥
Bẖā▫ī re mail nāhī nirmal jal nā▫e.
O Siblings of Destiny, filth is washed away by bathing in the Pure Water of the Name.
The tuk in English uses the idea of "filth" but our Gurus were compassionate men and not given to denouncing us. Let us think instead of things that "clutter" our mind. There is a remedy. Move the clutter aside so that we can be steady and focus on nirmal jai which leaves our minds "clear" "Nirmal" ... Just like opening a stale closet of past obsessions to let in fresh air, and with it something clean and worthwhile.
ਨਿਰਮਲੁ ਸਾਚਾ ਏਕੁ ਤੂ ਹੋਰੁ ਮੈਲੁ ਭਰੀ ਸਭ ਜਾਇ ॥੧॥ ਰਹਾਉ ॥
Nirmal sācẖā ek ṯū hor mail bẖarī sabẖ jā▫e. ||1|| rahā▫o.
You alone are Perfectly Pure, O True Lord; all other places are filled with filth. ||1||Pause||
So then we are told here in the rehao line that we have a choice. One direction is for munn to dwell in a clean, fresh place imbued with the Nirmal sacha. Or munn can dwell in an cluttered place invented for it by centuries of fear and superstition passed from one generation to the next.
ਹਰਿ ਕਾ ਮੰਦਰੁ ਸੋਹਣਾ ਕੀਆ ਕਰਣੈਹਾਰਿ ॥
Har kā manḏar sohṇā kī▫ā karṇaihār.
The Temple of the Lord is beautiful; it was made by the Creator Lord.
ਰਵਿ ਸਸਿ ਦੀਪ ਅਨੂਪ ਜੋਤਿ ਤ੍ਰਿਭਵਣਿ ਜੋਤਿ ਅਪਾਰ ॥
Rav sas ḏīp anūp joṯ ṯaribẖavaṇ joṯ apār.
The sun and the moon are lamps of incomparably beautiful light. Throughout the three worlds, the Infinite Light is pervading.
Sounds good!
ਹਾਟ ਪਟਣ ਗੜ ਕੋਠੜੀ ਸਚੁ ਸਉਦਾ ਵਾਪਾਰ ॥੨॥
Hāt pataṇ gaṛ koṯẖ▫ṛī sacẖ sa▫uḏā vāpār. ||2||
In the shops of the city of the body, in the fortresses and in the huts, the True Merchandise is traded. ||2||
Within us is the capacity to find the sach sauda, which comes to us from the Satguru. Then there will be not dirty deals. We can find it if we look earnestly. It will be harder if we have to carry our obsessions with us.
ਗਿਆਨ ਅੰਜਨੁ ਭੈ ਭੰਜਨਾ ਦੇਖੁ ਨਿਰੰਜਨ ਭਾਇ ॥
Gi▫ān anjan bẖai bẖanjnā ḏekẖ niranjan bẖā▫e.
The ointment of spiritual wisdom is the destroyer of fear; through love, the Pure One is seen.
This is the way to unload the mental baggage.
ਗੁਪਤੁ ਪ੍ਰਗਟੁ ਸਭ ਜਾਣੀਐ ਜੇ ਮਨੁ ਰਾਖੈ ਠਾਇ ॥
Gupaṯ pargat sabẖ jāṇī▫ai je man rākẖai ṯẖā▫e.
The mysteries of the seen and the unseen are all known, if the mind is kept centered and balanced.
This is what we gain if we do unload the mental baggage.
ਐਸਾ ਸਤਿਗੁਰੁ ਜੇ ਮਿਲੈ ਤਾ ਸਹਜੇ ਲਏ ਮਿਲਾਇ ॥੩॥
Aisā saṯgur je milai ṯā sėhje la▫e milā▫e. ||3||
If one finds such a True Guru, the Lord is met with intuitive ease. ||3||
ਕਸਿ ਕਸਵਟੀ ਲਾਈਐ ਪਰਖੇ ਹਿਤੁ ਚਿਤੁ ਲਾਇ ॥
Kas kasvatī lā▫ī▫ai parkẖe hiṯ cẖiṯ lā▫e.
He draws us to His Touchstone, to test our love and consciousness.
ਖੋਟੇ ਠਉਰ ਨ ਪਾਇਨੀ ਖਰੇ ਖਜਾਨੈ ਪਾਇ ॥
Kẖote ṯẖa▫ur na pā▫inī kẖare kẖajānai pā▫e.
The counterfeit have no place there, but the genuine are placed in His Treasury.
Here is where we learn that continuing on with all that baggage is a waste.
ਆਸ ਅੰਦੇਸਾ ਦੂਰਿ ਕਰਿ ਇਉ ਮਲੁ ਜਾਇ ਸਮਾਇ ॥੪॥
Ās anḏesā ḏūr kar i▫o mal jā▫e samā▫e. ||4||
Let your hopes and anxieties depart; thus pollution is washed away. ||4||
Who would not make that trade? The trade of clutter for something that erases the source of fear, anxiety and false hope that our minds will save us?
So there can be no sitting on the fence, playing both ends against the middle, hoping to get it right by giving some credit to Gurbani and some credit to the occult. Guru Nanak, and the Guru Sahibhan, never rebuked humankind for belief in the occult. It was their way to teach not scold. Rebuke of those who misuse power and create fear and terror from greed and haumei is the exception. None ever said, "Do not believe in these things." Instead they point to the choices before us. Our own homes, huts, fortresses (our consciousness) can be cluttered with fears and obsessions; or there can be the pure light of sat. We can live in nirmal, or not. We can walk one path or the other, but not both. Take your pick!
Merchants of fear who sell astrology, spells, mantars prey on our fears. They run a protection racket for the fears we have created ourselves. It is worth discussing whether the impact of this shabad is to fill our minds with the merchandize of the Sat, leaving no room for anything other than Guru's wisdom.