"until the 20th century, all mainline protestant churches opposed birth control . . .
So, were such folks basing what they believe on the Bible and leading by the Holy Spirit during the four hundred years or so when they taught that contraception was a sin, or are they being led by the Bible and Holy Spirit now that they teach the exact opposite?
Would the Holy Spirit teach one thing as truth one day and the exact opposite as truth the next?
The fact that "most Protestants" don't oppose birth control shows that "most Protestants", (and "most Catholics" for that matter since they ignore what the Church teaches), no longer as concerned about their relationship to Christ as they are about their relationship to their libido.
no the holy spirit would not change His teachings....that's the point...Protestants do...and often, and as it suits their means..
Catholics do not change their views on birth control (artificial) some unfortunately for them, choose to ignore the RULES