Thoughts on #1abib #moedim #determiningthefeastdates: TL:DR - Do the calendar with fellow believers in your area. I.E. If they are running on Hillel II, do Hillel II.
When the question came up to do this subject, I had typed out a long response but thought it best to use it as a post once it was the topic. From what I have seen and studied out, a lot of people are passionate about their calendar choice. I can't tell you how many times I have run into people, with widely different viewpoints on the calendar, and they see their calendar as 100% correct. The one that has been in use since time began.
There is only one major problem with this: the timepeice that we are all to keep time with (Sun, Moon, and stars) have been broken by YHWH and the clock is off. So, no one today is keeping the same calendar as Adam or Moses or even Yeshua.
In Joshua 10, Joshua asks YHWH to make the Sun stand still, and both the Sun and the Moon stay in their place. No mention of the stars stopping, so we could assume this took the Sun and the Moon out of sync with the stars. If we don't want to assume, we still have further evidence:
In 2 Kings 20:1-11 / Isaiah 38:1-8 , Hezekiah is talking with YHWH and asks for the shadow of the Sun to step back 10 steps. Taking the Sun out of sync with the Moon and the stars.
Some say the sun dials had 360 steps, which makes sense as I'll show in a minute. Best guess is that moving 10 steps back would be about 40 minutes.
Now imagine you had a old gear clock and you did the same to it. Took one of the arms and forced it back 40 minutes. What do you think would happen to the time displayed over time? A week later? A year later? 2,000 years later?
What may have been a minor time sync problem, could turn into a major time sync problem. And as no one would live long enough to see the shifts "in real time" as they are happening, we just assume it has always been this way.
However, there is recorded history of a time when major shifts, around the time of Hezekiah, did happen and the world didn't know what to do. I like to refer to https://360dayyear.com, but there are other sites as well. This and other sites show that the ancient world, up until around 700 B.C. (During the reign of Hezekiah) were keeping a 360 day calendar.
There are even some accounts of when the Romans found extra days over the 360 in the year, they didn't count them and wouldn't pay their soldiers as "those weren't real days".
We see in Noah's account and also in Revelation, for their math to work on how many days passed in their timeframes given, a 12-month, 30-day month, 360-day year calendar would be what they are basing their times on.
As during John's time, there wouldn't have been a 360-day consistent year, to me, this shows that YHWH in the End Times will once again adjust His clock and bring the Sun, Moon, and Stars back into sync and we will again have a perfect 360-day year. Some believe this is the great Earthquake in Isaiah.
So, ALL that to say, no one today is going to have a perfect calendar, because the clock is off. Some read the clock as 1:45, others as 9:05, others read it in a way that makes you wonder if they are even looking at the clock (I won't say who). Regardless, find a group, and keep the Feast Days with them. I'll tell you from experience, that keeping the Days with people is a lot better than keeping them alone. I know there are a lot of folks around the world that are looking for that fellowship. Don't let calendar issues be what keeps you from it.
The calendar I currently follow has flaws, but as I've explained in this post, I expect that. I used to keep Hillel II until I started digging into calendars. Then I joined a group that kept a different calendar. This is what caused me to do a ton of research. I almost changed to an all together different calendar than Hillel and what we are currently using. In the end, I realized that everyone has great points. Everyone has Biblically sound reasons for the calendars they keep. Just like many other issues in Torah and the Bible that we all go back and forth on, we will all be on the same calendar when He sets His Kingdom up on Earth.