In comparing these figures with those already given for the Roman Catholic Church, it should be noted that the Roman Catholic figures include as members all baptized persons, whether confirmed or not. The Protestant practice is to in- clude in a count of members only those who were communicant members when the enumeration was made. The estimated Protestant population, counting all members of any family in which anyone is a communicant member of a Protestant church, grew from 30,000,000 in 1906 to 40,000,000 in 1920, an increase f 33'3%- The increase of Roman Catholic population during the same period, as above shown, was 26%. An exact com- parison between the growth of population and the growth of church membership is impossible owing to the fact that the population census and the religious census are not taken the same year but several years apart. A comparison of figures, however, indicates that the population of the continental United States increased between 1910 and 1920 at an average annual rate of 1-5%. During the period from 1916 to 1920, on the other hand, church membership increased at an average annual rate of 2-5%.
The World War. Perhaps the most striking phase of the work of the churches during the decade 1910-20 was their service in the World War. As soon as the United States entered the war almost every church or denomination organized a war com- mission or council to aid the Government in securing chaplains and in similar tasks. The war-work commissions of the Prot- estant churches cooperated in the General War-Time Com- mission of the Churches; while the activities of the Roman Catholic Church were carried on through the National Catholic War Council. The General War-Time Commission, besides largely developing the spirit of cooperation, was able to under- take activities which were impossible to the separate church bodies, such as surveying the needs and opportunities for religious work in the camps and war communities; coordinating the plans and efforts of the denominational commissions; representing the Protestant churches in relations with the war and navy departments; securing qualified chaplains; providing for the moral and religious welfare of negro troops; supplying religious ministration for interned aliens; arranging for the wel- fare of workers in communities engaged in the manufacture of munitions and in shipbuilding; and stimulating the churches to cooperate with the Government and welfare agencies in the various campaigns for funds, food conservation, personal serv- ice, etc. Equally important work was done by the National Catholic War Council. Of the effect of the war on the American churches very little can be said. Expectations that the men would bring back from their experiences in the army or navy fresh interpretations of Christianity, and that the churches would apply in their local work many of the methods found effective among soldiers, have not been realized. Positive results, however, are: gain in practical cooperation among the churches, a larger place for the Church in the life of the community, stimulation and enlargement of missionary work and greater attention to education.
Cooperation and Union. The decade 1910-20 was note- worthy among the Protestant churches for the development of cooperation and union. This appears in three fields: (i) local cooperation and federation, (2) cooperation of adminis- trative bodies, (3) denominational federation and union. In the first of these, cooperation in local communities, there is to be noted a growing movement in the formation of federated churches, i.e. two or more churches joining their activities under the same pastor while each retains its separate organization and denominational affiliation. Several hundred of these federated churches have been organized, the Home Missions Council having (1921) a list of about 200. In many localities the growth of a community consciousness has expressed itself in one de- nominational church, serving the whole community, often having an associate membership for Christians of other de- nominational preferences, and carrying on a variety of activities for the uplift of the community. A notable development has been the exchange of territory between denominations in some
of the older states, like Vermont, and the allocation of territory to home mission agencies of different denominations in newer sections, such as Montana, Alaska and Porto Rico; In larger cities federations or councils of churches have steadily grown in number and importance. Under the leadership of the Com- mission on Councils of Churches of the Federal Council of the Churches of Christ in America, first organized in 1912, such federations have been formed in nearly 50 cities, having strong local financial backing and employing one or more secretaries. Among their activities are social service, evangelism, religious education, religious publicity and missions. Important con- ferences on interchurch work were held in Pittsburg in 1917 and in Cleveland in 1920.
In the second field of cooperation, that of denominational administrative boards, the development has been principally in missions and education, culminating in the Interchurch World Movement. The World Missionary Conference held in Edinburgh in 1910 powerfully stimulated cooperation among foreign mission boards, and the Continuation Committee has represented the American boards in organizing cooperative work in foreign mission fields. The similar Congress on Christian Work in Latin America, held at. Panama in 1916, was the out- come of a conference in 1914 of missionaries and Protestant mission boards working in Mexico. Among its results is the permanent Committee on Cooperation in Latin America, which unites in many forms of service most of the boards having work there. The Foreign Missions Conference of North America, organized in 1893, which officially represents the Protestant foreign mission boards of the United States and Canada, has during the decade 1910-20 greatly enlarged its sphere of activ- ities, particularly through its Committee of Reference and Counsel, its Board of Missionary Preparation, and its Com- mittee on Religious Needs in Anglo-American Communities. In home missions cooperation has been greatly furthered through the Home Missions Council, organized in 1908, which aims to prevent duplication of effort and to provide for adequate occupation of fields and in general to coordinate the home mission agencies of the denominations it represents. Similar cooperation has developed among women's mission boards, through the Council of Women for Home Missions (1908) and the Federation of Women's Boards of Foreign Missions of North America (1916). The decade 1910-20 stands out beyond all previous decades in missionary cooperation, so that by 1921, with but few exceptions, the leading Protestant missionary boards were thoroughly committed to this policy. The same was true, in scarcely less measure, of the educational boards. In 1911 these united in the Council of Church Boards of Educa- tion, which collated information, studied the standardization of courses in church schools and colleges, and held conferences of university pastors and other church workers in the larger institutions. The Sunday-school agencies of the denominations formed in 1911 the Sunday School Council of Evangelical Denominations, for cooperation in educational, editorial, mis- sionary and publishing activities.
The Interchurch World Movement of North America was organized by representatives of Protestant mission boards in 1918, primarily to meet the urgent need of expansion in mis- sionary work as a result of the war. It rapidly extended its scope, however, to include surveys of all Christian work at home and abroad, missionary education, recruiting for the ministry and mission service, and a simultaneous appeal for funds by all cooperative church bodies. The movement failed, owing, among other things, to unbusinesslike financial operations and irresponsible activity on the part of some of its leaders; but it revealed a widespread spirit of cooperation.
In the third field of cooperation and union, that of the de- nominations and church bodies as ecclesiastical organizations, the development has proceeded along two lines: federation and organic union. The first is represented especially by the Federal Council of the Churches of Christ in America, organ- ized in 1908, in which about 30 Protestant denominations are officially represented. While retaining their autonomy the
