Muhammed, while establishing his new religion, drew inspiration from the Jews and Christians. He incorporated the concept of a monotheistic God, prophets, and angels into Islam, which he adopted from these religions. However, he also wanted to include elements like the Ka'aba and Hajj in Islam for political reasons, as they held significant importance in the Arab world.

One Arab custom involved designating four sacred months out of the twelve, during which wars and the looting of trading caravans were prohibited. This custom was crucial for their economy as it allowed for the movement of caravans and trade with other tribes during those 4 peaceful months.

The ancient Arabs themselves initiated this tradition based on their needs, later attributing it to the idol gods, whom they believed commanded them not to shed blood or loot caravans during those four months.

Additionally, the Arabs followed the Lunar Calendar, which had the flaw of being ten days shorter than the Solar Calendar. This flaw had a significant impact on the lives of the Arab people, as it made it challenging to align Hajj events and trade caravans with months of favorable weather. Due to the Lunar Calendar, Hajj would sometimes fall during extremely hot or cold weather. Similarly, many trade goods were also dependent on weather conditions and could not be traded during the off-season.

Not only did the Arabs of that time follow the Lunar Calendar, but the Jews also followed a similar calendar. However, the Jews recognized the flaw in the Lunar Calendar and introduced a reform by adding an extra month every three years to make it align with the Solar Calendar.

Even the Arabs of the pre-Islamic era learned this from the Jews. They introduced the practice of adjusting the timing of the four sacred months according to weather conditions to ensure that Hajj and trade could take place in pleasant weather, enabling people to travel easily.

However, the writer of the Quran (Muhammad) not only retained the flawed Lunar Calendar but also prohibited the practice of adjusting the timing of the four sacred months.

(Quran 9:36-37)

Indeed, the number of months with Allah is twelve [lunar] months in the register of Allah since the day He created the heavens and the earth; of these, four months are sacred. That is the correct religion, so do not wrong yourselves during them. And fight against the disbelievers collectively as they fight against you collectively. And know that Allah is with the righteous [who fear Him]. Indeed, the postponing [sacred months] is an increase in disbelief by which those who have disbelieved are led [further] astray. They make it lawful one year and unlawful another year to correspond to the number made unlawful by Allah and [thus] make lawful what Allah has made unlawful. 

Since there is no All-Knowing Allah present in the heavens, and Muhammad was himself creating this religion of Islam and Quran, and he himself belonged to that culture of the time of ignorance, that is why Muhammad made this double mistake in Quran:

  1. Firstly, Muhammad chose this faulty and deficient Lunar Calendar, instead of the solar calendar. (Note: Solar Calendar was already present in the world at the time of Muhammad, but Muhammad didn’t know about it as he lived in an area where people were ignorant of the concept of solar year)
  2. And moreover, Muhammad also made this claim in Quran that these 12 months existed since the beginning of the universe

But how is it possible, while:

  • There existed no moon and earth, no day and night, no months and years at the beginning of the universe. 
  • The earth came into being only 9 billion years after the creation of the remaining universe.
  • And the moon came into being even after planet Earth.

So, how is it possible that the "System of the Universe" revolved around 12 Lunar Months, since the beginning of the universe?

But obviously, Muhammad didn’t know it.

What to talk about the lunar year, but even the solar year also has nothing to do with the system of the heavens, as the sun was also not present at the time of the creation of the universe. 

Why did the writer of the Quran declare these 4 months sacred?

Muslims have long been perplexed by the significance of the four sacred Lunar months mentioned in the Quran and why they were designated as such for the past 14 centuries. It should be noted that the month of Ramadan is not included among these four sacred months.

Out of the four months, three (Dhul Qadha, Dhul Hijjah, and Muharram) occur consecutively. During these months, trade caravans journeyed in peace for the Hajj pilgrimage. The fourth month, Rajab, witnessed trade caravans embarking on the 'Umra journey to the Kaaba.

In the pre-Islamic era, the Arabian Peninsula was comprised of various tribes, and their livelihood often involved raiding trade caravans. To ensure peaceful trade for Hajj and 'Umra, the Arabs deemed these four months as sacred.

However, with the advent of Islam and the unification of the Arab region under a single state, trade caravans were no longer subjected to looting throughout the year. Consequently, the necessity of safeguarding trade caravans during these specific months ceased to exist.

This raises the question: Why did Allah only declare these four months as sacred, prohibiting bloodshed and looting during this limited period? Logically, if there truly was an Allah, the decree would have been for all twelve months to be sacred, disallowing violence and looting throughout the entire year.

It seems incongruous that a divine being would restrict people from engaging in war, spilling blood, and looting trade caravans for only four months, while permitting such actions during the remaining eight months.

Following the establishment of a unified Arab state, wars and the looting of trade caravans became non-existent throughout the year. Consequently, contemporary Muslims have limited knowledge of these four sacred months and the reasons behind Allah's declaration.

In reality, there is no higher power, and it was Muhammad himself who adhered to this custom from the pre-Islamic era of ignorant practices. The sacredness attributed to these four months is not inherent, but rather stems from weather conditions and trade activities in the Arabian region.

Furthermore, if Allah had indeed proclaimed these four months as sacred since the creation of the heavens and the Earth, one would expect to find references to them in Jewish and Christian scriptures. However, there is no mention of Hajj, 'Umra, the twelve Lunar months, or the four sacred months in Jewish or Christian texts.

Since Jews and Christians did not have the annual obligation of Hajj or 'Umra, the concept of four sacred months did not exist for them, as it did for the pre-Islamic pagans.

In the era of ignorance, the twelve-month Lunar Calendar was followed worldwide. However, aside from the pagan Arabs, no other community regarded these four months as sacred. This highlights the fact that only the pagan Arabs felt the need for an annual Hajj and 'Umra pilgrimage.

Islam Apologists: Allah chose the Lunar Calendar to break the habits

Islam apologists argue that the Lunar Calendar is not flawed, but rather a deliberate choice by Allah to disrupt habits and challenge individuals to perform Hajj in extreme weather conditions, as well as fasting during extreme heat or cold.

However, this excuse holds little weight. Not even Allah himself presented this justification; it was fabricated later by Islam apologists.

If the repetition of events at specific intervals is truly undesirable, then why does nature adhere to this rule? Why do the four seasons repeat themselves at predictable intervals? Why do crops grow in accordance with these seasons? Why do birds migrate at the same time each solar year?

It should be noted that nature also contains variations within itself. The length of days fluctuates based on the seasons, leading to changes in sleeping patterns, waking times, and meal schedules. Even prayer times are influenced by these variations.

However, repetition is just as necessary in nature as variation. Nature repeats itself at the same time for annual events, as it is crucial for the growth of crops, the trade of goods, and the functioning of human life.

Aligning ourselves with nature is essential. Whenever we go against nature, we make mistakes. Opposing nature can lead to the destruction of businesses, as individuals cannot leave their crops unattended to embark on the Hajj pilgrimage.

The start of the “Weekly System” and Islam copying it from earlier cultures

The system of dividing a lunar month into four weeks is inherently flawed. A lunar month consists of approximately 29.53 days, making it impossible to evenly divide into four equal weeks.

The system of the Lunar Year has its origins in Sumerian culture, dating back to the era of ignorance. Interestingly, Islam still followed it while Islam itself is a product of the era of ignorance. 

https://www.livescience.com/45432-days-of-the-week.html
The seven-day week originates from the calendar of the Babylonians, which in turn is based on a Sumerian calendar dated to 21st-century B.C. Seven days corresponds to the time it takes for a moon to transition between each phase: full, waning half, new and waxing half. Because the moon cycle is 29.53 days long, the Babylonians would insert one or two days into the final week of each month.

Just as the Jews declared Saturday as a sacred day, Islam designated Friday as a sacred day. According to Muhammad, Friday was also considered sacred by previous nations, but they later deviated from this belief and revered other days instead.

Sahih Muslim, Hadith 856b:
Huraira reported Allah's Messenger (ﷺ) as saying: We were guided aright to Friday (as a day of prayer and meditation), but Allah diverted those who were before us from it. 

Moreover, Muhammad also claimed that Adam was created on the day of Friday, and on this day, he was expelled from paradise, and on Friday he died. 

Sahih Muslim, Hadith 854b:
Abu Huraira reported the Messenger of Allah (ﷺ) as saying: The best day on which the sun has risen is Friday; on it Adam was created. on it he was made to enter Paradise, on it he was expelled from it. And the last hour will take place on no day other than Friday.