I'm learning so much amazing things. Thank you for this wealth of information!Reading the Bible with an open mind gives you an understanding of the will of God, which might be different in practice that the traditions that were taught for well over 400 years now. The Amish are germanic in origin. Martin Luther King Jr. is a hero in the older generation of Amish for his translation of the Luther German Bible which most of them still use in worship services. There are a few districts that will preach in english if they have english speaking visitors.
I don't know if the Amish split from the Lutherans. I'm not much of a historian.
Jacob Ammon is commonly referenced for starting the Amish group we know of today. The Amish actually split off from a Mennonite group, commonly known as followers of one by the name Menno Simons. There are various others that I don't have names for right now that were also involved in getting these groups started.
This link is a decent history on the different groups and subgroups within the larger group.
https://en.wikipedia.org/wiki/Subgroups_of_Amish