In the spring of 1552 John Calvin in Geneva received a letter from the Polish reformer John à Lasco, recently appointed superintendent of the new Stranger Church in London. The church had two congregations, a Dutch and a French, and the French had recently been disturbed by controversy when a newcomer criticized an aspect of the church's teaching on the grounds that it diverged from that of the Genevan church. At issue was whether the Virgin Mary should be given the title the Mother of God. Calvin's reply was careful but firm. While not denying the difference of opinion he nevertheless sharply reproved those who had disturbed the church by invoking his name, or as he put it, making “an idol of me, and a Jerusalem of Geneva.” For as he went on, the more critical issue was that of church order, and unity: “If those who have stirred up these strifes among you have taken occasion to do so through the diversity of your ceremonies, they have ill understood in what the unity of Christians consists, and how every member ought to conform himself to the body of the Church in which he lives.”