For full reports and exact statements of the CRCNA position on a particular issue, see references provided below.
Church membership and membership in a labor union are compatible as long as the union does not warrant or champion sin in its regular activities. Church members should discontinue membership in any unions whose common practices are clearly in conflict with the principles of the Word of God. Christian conscience cannot condone membership in a union if it continues in sinful practices in spite of protests against them. Membership in unions which have engaged in sinful practices does not of itself make one liable to ecclesiastical censure, but if church members themselves are guilty of acts contrary to the Word of God, the usual means of discipline should be applied. Churches should be aware of the practices of labor organizations in their communities and vigorously emphasize the scriptural principles regarding the relation of the Christian to the world and the organizations of the world.
The CRC has dealt with the issue of labor unions several times in its history. From the 1880s to the 1940s the following matters were discussed: whether church members ought to be members of labor organizations, whether members of a union are responsible for its decisions and acts, and which labor unions were appropriate for church members. In 1904, 1928, 1930, and 1943, synod reasserted its basic position with regard to unions. In 1934, 1936, and 1943, synod recommended the Christian Labor Organization for moral and financial support. Synod 1965 adopted resolutions of the Reformed Ecumenical Synod regarding Christian organizations. This discussion went beyond labor organizations to include social and political organizations.
Acts of Synod 1916, pp. 38-39
Acts of Synod 1942, pp. 132, 361-86
Acts of Synod 1943, pp. 102-3, 381-403
Acts of Synod 1964, pp. 74-76, 326-28
Acts of Synod 1965, pp. 118-21, 187-92