What is the ruling on using the Gregorian calendar instead of the Hijri calendar?

It is preferable to use the Hijri calendar, which relies on lunar months, for Allah Almighty made them appointed times for mankind and for the Hajj, fasting, and the sacred months, as stated in His saying: "They ask you about the new moons. Say, 'They are appointed times for people and for the Hajj,'" and His saying: "Indeed, the number of months with Allah is twelve months in the register of Allah from the day He created the heavens and the earth; of these, four are sacred. That is the correct religion." It is mentioned that legal rulings must be tied to the Arabic months and years. There is no explicit text prohibiting the use of the Gregorian calendar, but it is better to adhere to the Hijri calendar because it is the one adopted in Islamic law.