The American church denominations rejected Darby's ecclesiology but accepted his eschatology. These are scripture (hermeneutics), the church (ecclesiology) and the "plan of salvation" (soteriology). Here Metropolitan John develops critically the eucharistic ecclesiology of Nikolai Afanassief. Important topics they address include ecclesiology, the sacraments, and the role of bishops. Federalism also finds expression in ecclesiology (the doctrine of the church). Reformed ecclesiology or the teachings about the Christian Church. As in "political federalism", in presbyterian ecclesiology there is shared sovereignty. It was a call for Southern Baptists to return to Biblical ecclesiology. Alexei had strong leanings towards archaeology and ecclesiology. They discussed Old Catholic Church ecclesiology, "highlighted in the Preamble" of the Statutes. In 1937 Congar founded the "Unam Sanctam" series, addressing historical themes in Catholic ecclesiology. Vatican II sought to clarify the ecclesiology stated in Vatican I. Vatican II sought to correct the unbalanced ecclesiology left behind by Vatican I. Gregory was also a prominent proponent of Eastern ecclesiology at the First Vatican Council. Tierney's work focused mainly on medieval ecclesiology and political theory.