King James felt it his responsibility to reunite the churches of Christendom. He never wanted to carry this out at the expense of truth, however, as can be seen by his refusal to submit to the Roman Catholic Church. The pope was eager to convert James, sending gifts and rosaries to his wife, but James had them returned. In fact, James chose to work with definitively Reformed theologians to further his cause.
The most ambitious plan was crafted with the help of Peter Du Moulin of Paris. According to their combined efforts, the Reformed churches of England and France would lead the effort, seeking to obtain alliance with the Swiss and Dutch churches. From there, the Lutherans would be invited. W. B. Patterson writes:
Du Moulin’s plan, with twenty articles, sought to find a basis for bringing together the Reformed churches, including the Church of England, and, subsequently, for bringing together these churches and the Lutheran churches. This would be done in two stages by means of an international assembly held with the support of the civil rulers of the Protestant states, especially the king of Great Britain, who is described in the first article as “the greatest and most powerful” of the sovereign princes of countries not under the subjection of the pope. The international assembly described in the plan would be a meeting of two theologians sent by the British king, two by the churches of France, two by those in the Netherlands, two by the Swiss cantons, and “one or two from each prince of Germany of our confession.” In addition, King James and the Elector Palatine might seek the support of some of the Lutheran princes, especially the king of Denmark and the dukes of Saxony, Wurttemberg, and Brunswick, in sending representatives there. The deputies at the assembly would put on the table the Reformed confessions of the various churches, including those of England and Scotland, and draw up a common confession. Some matters “not necessary to salvation” might be passed over, including the opinions of Arminius on predestination. Once this doctrinal accord had been drawn up, the delegates would formally declare that their churches did not condemn each other because of differences in ceremonies and ecclesiastical polity. The deputies would then seek to meet with deputies of the Lutheran churches in order to enlarge the association. On the perennially contentious issues of the necessity of baptism, the manner of Christ’s presence in the Lord’s Supper, and the reception of the body of Christ in the Supper, agreement would be sought with the Lutherans on broad theological principles. But where complete agreement could not be reached, differing views would be tolerated among the churches. At the conclusion of the assembly a celebration of the Lord’s Supper would be held at which the Lutheran pastors and the others would communicate together.
~ King James VI and I and the Reunion of Christendom pg. 161
He concludes that:
After their return home, the deputies would submit their work for the approval of their respective churches, while the princes would seek to abolish the names of Lutheran, Calvinist, and Zwinglian in favor of the name Christian Reformed Churches.