 Calvin 's authority was practically uncontested during his final years , and he enjoyed an international reputation as a reformer distinct from Martin Luther . Initially , Luther and Calvin had mutual respect for each other . However , a doctrinal conflict had developed between Luther and Zurich reformer Huldrych Zwingli on the interpretation of the eucharist . Calvin 's opinion on the issue forced Luther to place him in Zwingli 's camp . Calvin actively participated in the polemics that were exchanged between the Lutheran and Reformed branches of the Reformation movement . At the same time , Calvin was dismayed by the lack of unity among the reformers . He took steps toward rapprochement with Bullinger by signing the Consensus Tigurinus , a concordat between the Zurich and Geneva churches . He reached out to England when Archbishop of Canterbury Thomas Cranmer called for an ecumenical synod of all the evangelical churches . Calvin praised the idea , but ultimately Cranmer was unable to bring it to fruition . 
