Reverend W.C.A. Martens served the congregation from 1915-1918. Plans for a new church building were discussed during this time. Such discussion culminated with the Voters’ Assembly creating a Building and Sinking Fund to be prepared when the time came to rebuild the church at a favorable location. Reverend E. F. Schueler guided the congregation following Pastor Martens’ departure, from 1918-1922. In 1918 the Young People’s Society affiliated with the International Walther League. In 1921 the original high tower of the church was removed.
Pastor C.A. Weiss served St. John’s congregation for the longest period of any pastor (thus far) from 1922-1946. The German language was being used less and less with Pastor Weiss conducting German services only two Sundays a month in addition to the regular English services. Sunday German services were dropped entirely in September 1927. For the next five years the only German service conducted was the Maundy Thursday communion service.
There were numerous financial problems during the depression years. The Building Fund especially suffered from a lack of gifts, though a new parsonage was purchased from the Building Fund in 1943. During June 1937 the congregation celebrated its 100th Anniversary with special serves each Sunday and a fellowship banquet. Much redecoration was done prior to the celebration. Also during this time, Miss Zelle retired as organist in 1944. Mr. Elmer J. Holzgraefe served as organist and choir director beginning in 1944 until 1986.
Upon Pastor Weiss' retirement in 1946, Pastor Edwin H. Hahn assumed the pastorate. In 1947 the Voters' Assembly officially adopted the present name, “The Lutheran Church of St. John.” The Men's Club was reorganized in 1946, at which time they also became affiliated with the Lutheran Laymen's League (LLL). The financial condition was greatly strengthened. Regular gifts began flowing into the Building Fund and the congregation once again thought about building a new church.
In 1953 Pastor Hahn accepted a call to serve a mission congregation in Urbana, IL. Pastor J.C. Landskroener succeeded Pastor Hahn. Under his leadership plans were made and realized for the relocation of the church. A successful financial drive for the new church began in November 1959. A tract of more than six (6) acres of land was purchased for $25,000 in 1960 on East State Street. Architect Don Hafner’s plan for the new church and educational unit was presented to the congregation on May 28, 1961. These plans were adopted later by the Voters’ Assembly. The ground-breaking ceremony for the present sanctuary was held on October 29, 1961 with Pastor L. J. Wyssmann, circuit counselor and pastor of St. James Lutheran Church, Quincy, delivering the sermon. The cornerstone was laid on August 12, 1962. The new sanctuary was dedicated on April 12, 1963. Final costs for the sanctuary, new parsonage, and furnishings were around $300,000. It is interesting to note that the old church altar, pews, pulpit, and lectern were purchased by Central Baptist Church for $1,000. The altar now can be seen at the Gardner Museum of Architecture in Quincy.
Besides building a new edifice, the congregation also began the "Mary and Martha Guild" in 1961. This organization and the existing Ladies’ Aid were affiliated with the International Lutheran Women’s Missionary League. Also during this time, St. John’s joined with other area congregations in sponsoring a religious television program called "Chart and Compass". And in 1960 a joint “Preaching, Teaching, Reaching” mission was held.
Pastor Landskroener received a call from a congregation in Evansdale, Iowa, and left on April 23, 1963, a few days after the new sanctuary was dedicated. Reverend Herbert Hallerberg was then installed as pastor. The years following 1962 were very busy for the congregation as they settled into their new home. An electric carillon system was installed, communion was offered twice a month (and now the communicants no longer had to sit in a reserved section), a youth group was started, the former church property and parsonage were sold, and various external enhancements were made to the new building. Perhaps the biggest “enhancement” to the building was the installation of air conditioning, which cost only $4,000 (labor was provided by congregational members). By October 13, 1968, the congregation paid off their mortgage and became "debt free". After twelve years of service, Pastor Hallerberg announced his retirement, which was effective on July 1, 1976.