This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
The Westminster Assembly did not sit at the invitation of a pope, a patriarch or even an archbishop. It sat because Parliament summoned it, in the middle of a civil war it had not yet won, to settle what the reformed Church of England would believe once the fighting stopped. That is worth pausing on, because nearly every other body in this section, an ecumenical council, a papal synod, met under a churchman's authority. Westminster met under a legislature's.
Its Scottish guests changed its outcome more than its English hosts may have expected. Parliament needed Scottish military help against the king, and the price of that help, the Solemn League and Covenant, was a seat at the table for Scottish commissioners who wanted the English church remade on Presbyterian lines, government by elected elders rather than by bishops. The commissioners could argue but not vote, yet the Confession that emerged in 1646 reads like a document built to satisfy Reformed churches on both sides of the border.
That is exactly what happened to it. England itself never adopted it: the monarchy returned in 1660, the bishops returned with it, and Parliament's own church settlement moved on without the Assembly's work. Scotland kept it, formally, in 1647, and from Scotland it traveled with Presbyterian emigration to become the confessional backbone of Presbyterian churches on every continent, a document written for one national church that ended up defining a worldwide one instead.