Age 82, passed away at Borgess Medical Center on Friday, June 23, 2017 due to injuries sustained in an automobile accident. Lois was born in Kalamazoo on June 29, 1934; the daughter of the late Ben and Mary (Van Dyk) Vander Klok. On April 22, 1955, she was united in marriage to Frederick P. Ritsema, who survives. Lois is also survived by her children, James (LuAnn) Ritsema, Melanie (Thomas) Botting and Joel (Kristi) Ritsema; nine grandchildren; two great-grandchildren; sisters, Marilyn Vander Kooy and Judy Koning; brother, Paul (Norene) VanDerKlok; and several nieces and nephews. A funeral service will be held at Centerpoint Church, 2345 N. 10th St., Kalamazoo, MI 49009, on Thursday, June 29, 2017 at 1:00 PM with Pastor Dar VanderWal officiating. Private interment will take place at Ft. Custer National Cemetery. Visiting hours will take place at Centerpoint Church on Wednesday, June 28, 2017 from 2:00 to 4:00 and 6:00 to 8:00 PM. Memorial contributions in Lois' memory may be made to Kalamazoo Christian School Association or Gideon's International, c/o the funeral home. Family and friends may share a condolence message online at www.joldersma-klein.com.