If there is no reincarnation after death …

Respected Truth Sikhr ji
The question that you have asked often comes to our mind very often. Salvation, Dharmaraj, Heaven and Hell and Chaurasih Lakh etc. are all written in Gurbani. The fact is that the above words were very popular at the time when Guru Sahibs wrote Bani. The Guru Sahibs took the utensils as old but put their own things in them. This means that Guru Sahib used all these words in Gurbani but gave his own teachings. In Gurbani, transmigration, 84 m lives, salvation after death, all these things have been completely rejected. There is a Hukam of Gurbani about the Juni Chakra / Life Cycles.

ਕਈ ਜਨਮ ਭਏ ਕੀਟ ਪਤੰਗਾ ॥ ਕਈ ਜਨਮ ਗਜ ਮੀਨ ਕੁਰੰਗਾ ॥
ਕਈ ਜਨਮ ਪੰਖੀ ਸਰਪ ਹੋਇਓ ॥ ਕਈ ਜਨਮ ਹੈਵਰ ਬ੍ਰਿਖ ਜੋਇਓ ॥
ਮਿਲੁ ਜਗਦੀਸ ਮਿਲਨ ਕੀ ਬਰੀਆ ॥ ਚਿਰੰਕਾਲ ਇਹ ਦੇਹ ਸੰਜਰੀਆ ॥ ਰਹਾਉ ॥
ਕਈ ਜਨਮ ਸੈਲ ਗਿਰਿ ਕਰਿਆ ॥ ਕਈ ਜਨਮ ਗਰਭ ਹਿਰਿ ਖਰਿਆ ॥
ਕਈ ਜਨਮ ਸਾਖ ਕਰਿ ਉਪਾਇਆ ॥ ਲਖ ਚਉਰਾਸੀਹ ਜੋਨਿ ਭ੍ਰਮਾਇਆ ॥
ਸਾਧਸੰਗਿ ਭਇਓ ਜਨਮੁ ਪਰਾਪਤਿ ॥ ਕਰਿ ਸੇਵਾ ਭਜੁ ਹਰਿ ਹਰਿ ਗੁਰਮਤਿ ॥
ਤਿਆਗਿ ਮਾਨੁ ਝੂਠੁ ਅਭਿਮਾਨੁ ॥ ਜੀਵਤ ਮਰਹਿ ਦਰਗਹ ਪਰਵਾਨੁ।।
ਜੋ ਕਿਛੁ ਹੋਆ ਸੁ ਤੁਝ ਤੇ ਹੋਗੁ ॥
ਅਵਰੁ ਨ ਦੂਜਾ ਕਰਣੈ ਜੋਗੁ ॥
ਤਾ ਮਿਲੀਐ ਜਾ ਲੈਹਿ ਮਿਲਾਇ ॥
ਕਹੁ ਨਾਨਕ ਹਰਿ ਹਰਿ ਗੁਣ ਗਾਇ।।(176)

It is explained in this Shabad that the human birth is to remember the Akal Purakh, that is, to possess the good qualities mentioned in Gurbani and to live a life of good wisdom according to them. 84 m Juni / Life Cycles means how many kinds of behaviours we change in a single day, like if we become greedy, then understand that we have entered the dog’s genesis / Life Cycles. So whatever we think, as the taste of the tongue in the genesis of the fish. So in the end Guru Ji explains that one has to take Guru’s good teachings and do good deeds in this life.
ਗੁਰਬਾਣੀ ਦਾ ਫੁਰਮਾਨ ਹੈ
ਪੁਛਿ ਨ ਸਾਜੇ ਪੁਛਿ ਨ ਢਾਹੇ ਪੁਛਿ ਨ ਦੇਵੈ ਲੇਇ ॥ ਆਪਣੀ ਕੁਦਰਤਿ ਆਪੇ ਜਾਣੈ ਆਪੇ ਕਰਣੁ ਕਰੇਇ ॥(53)
This means that Akal Purakh does nothing by asking the beings. Neither does he prepare the body by asking nor does he finish the body by asking. Akal Purakh, Himself knows this infallible law. So let us do good deeds in this life guided by Gurbani because Gurbani explains the point of Jeevan Mukti.
Gurbani does not Sermons of any rebirth. It is a matter of doing good deeds in this very birth. If we do deeds according to Gurbani, then understand that we are in life Otherwise let us consider ourselves spiritually dead.