It ain't my idea, it's God's very specific scriptural way of keeping time from the beginning
The 'International Standard' was only invented some 300 odd years ago and is eveb mathematically inconsistent [causing severe ,even religious, problems for many, especially those bizarrel religiously forbidden to cross the dateline for 2 days per week so that they can't have two or no sabbaths per week ... but also they cannot visit their kin on the other side of an arbitrary line at weekends ... sheer nonsense intaegral to the international system but not in God's original system!
It is no accident that God defined that the evening comes BEFORE the morning in the day... this is not what we are used to by our standards from Roman pagan TRADITION ,but God said that this is the way to keep holy days, defining what a day is from the beginning:
Gen 1:5 ... And the evening and the morning were the first day.
For explicit example:
Leviticus 23:32 .... from even unto even, shall ye celebrate your sabbath.
As for the knowledge of calculating time of Herusalem sunset around the globe, God made that available to man long before the time of Jesus the man and spread of the gospel to reach the House of Israel as Jesus said:
Matthew 15:24 But he answered and said, I am not sent but unto the lost sheep of the house of Israel.
and the House of Judah did not stray more than an hour's difference from accurate sabbath-keeping before then [an 'hour' was the very finest accuracy to which time was kept at that time]
The non-Jewish part of Israel, the "lost sheep" of the House of Israel to whom God sent Jesus' gospel message through the remanat of the Jews whom God gave to Jesus as apostles to do the job and sent them forth:
Matthew 10:6 But go rather to the lost sheep of the house of Israel.
, this House of Israel once had its own King, but God scattered them, the NON-Jewish MAJORITY of Israel, amongst gentile nations so that they lost their religion, the scripture says that God gave them up to worship other gods, and ceased to have their national identity, being absorbed into pagan gentile nations... they became gentiles to all but God... but God also promised to one day re-unite the old non-Jewish part of Israel with the smaller Jewish part and these would be the sons of God spoken of in the NT:
Hosea 1:10 ....and it shall come to pass, that in the place where it was said unto them, Ye are not my people, there it shall be said unto them, Ye are the sons of the living God. {in
: or, instead of that}
11 Then shall the children of Judah and the children of Israel be gathered together, and appoint themselves one head, and they shall come up out of the land: for great shall be the day of Jezreel.
Specifically there are 12 o the 14 tribes of Israel [Jacob adopted Ephraim and Manasseh , his grandsons as full sons and thus tribes of Israel, and Joseph had other sons to, the tribe of Joseph]
Thus by the time that the message was sent out to the scattered House of Israel, the knowledge was available to calculate sunse Jerusalem accurately enough and the spread of the Roman Empire paradoxically also spread the means of keeping holy days, the public sun-dial , ahtad of the spread of the gospel ...
Jesus confirmed that the Jews in the Holy Land were indeed keeping the true weekly and annual sabbaths by keeping them himself and also underlined that the savvaths were made by God for mankind ... a blessing from the beginning, quite completely independent of Israel's being commanded by God to KEEP them [sabbath existed LONG BEFORE the old covenant which is only about KEEPING God's holy days that already existed as a blessing to all that choose voluntarily to keep them ... and that is for ALL time ... the sabbaths are mentioned several times in prophecy of the FUTURE too!] :
Gen2:3 And God blessed the seventh day, and sanctified it
So God has NEVER defined time in arvbitrary unnatural 'timezones' ,which is inconsistent and only recently invented by mankind [under Satan] ... we can however see that even this corruption ,denying mankind the nlessing of god's holy sabbaths defined in scripture, is prophesied by God through Daniel:
Daniel 7:25 And he shall speak great words against the most High, and shall wear out the saints of the most High, and think to change times ....