Membership in the Affiliation of Christian Geologists is international and open to all who can assent to the purpose and principles of the ACG and who have the required educational or professional background in geology or related sciences.
The ACG is formally constituted as a division of the American Scientific Affiliation, a long-standing association of scientists who are Christians. Nevertheless the ACG functions with a degree of autonomy and it is not necessary to be a member of the ASA to be a member of the ACG.
All members shall assent to the statements of Purpose and Principles.
Both regular and associate members shall pay the full annual dues. Student member dues shall be set at 50% of the annual dues.
The statement of Christian faith of the ACG is identical to that of the ASA, that is:
We accept the divine inspiration, trustworthiness and authority of the Bible in matters of faith and conduct. We confess the Triune God as affirmed in the Nicene and Apostles' Creeds which we accept as brief, faithful statements of Christian Doctrine based upon Scripture. We believe that in creating and preserving the universe God has endowed it with contingent order and intelligibility, the basis of scientific investigation. We recognize our responsibility as stewards of God's creation to use science and technology for the good of humanity and the whole world.
Furthermore, as members of the ACG we subscribe to the understanding that investigation of the Earth and its history through geological methods is a valid enterprise that must be pursued with integrity and faithfulness to the canons of sound science.