How did the Amish figure out what period in history god wished them to be stuck in?

The Amish don't give a rat's a** about maintaining a lifestyle in regard to a particular period of history. Their culture is a direct reflection of their literal interpretation of the Bible. In regard to technology, the heads of each church district assess new technology and decide whether it would be counter to their beliefs and detrimental to their society, or can be accepted.

I know, huh?

Can you imagine the conversations among their founders?

"Well, everything invented before 1836 is fine, but anything after that is clearly inspired by Satan, so that's our cutoff date."

"Well hold on now, the steel plow wasn't invented by John Deere until 1837, and we really need to use those, so let's go with 1837 instead."

"Oh, ok. 1837 it is. Anything before that is godly, anything after that is evil and inspired by Satan. All in favor say Aye..."

:)

I think they just miss the lynchings of the time...KIDDING.

Apparently, that was when religion started taking to decline in the general public, and archaeologically, that's correct.

They rejected the immoral values of the times in which they were founded. The early 1700's.