It looks like Custance's "calvinism" is irrelevant.
It appears they like him for his goofy 'Gap-Theory' of Creation:
Historical Evidence of The Gap Theory
Pre-Geologic Age Almost without exception, the Gap theory is credited to Dr. George Chalmers of Edinburg University in 1814. Supposedly Dr. Chalmers introduced this theory in an attempt to harmonize the Genesis account with the vast periods of time demanded by uniformitarian geologists. It is then claimed to have been elaborated by George H. Pember in his work (Earth's Earliest Ages) in 1876, and finally popularized in the footnotes of the Scofield Reference Bible beginning in 1917. Today, it is said that only pinheads and nitwits of dubious scholastic background maintain a belief in the "Gap Theory". If, as it is today asserted, the theory can only be traced back to Dr. Chalmers, then the statement of its reason for introduction should not be discounted. On the other hand, if the theory antedates both Dr. Chalmers and any uniformitarian geologist, then it should and indeed must be investigated by any serious student of scripture to determine why such a Gap exist.
Mark E. Howerter, in his work "Creation VS Evolution: The Gap Theory Explained", follows the now accepted view when he wrote:
Uninformed Christians have propagated two theories that have tried to reconcile the Bible with evolution. They have done this because from kindergarten through graduate school it is taught that evolution is a proven scientific fact. Christians have swallowed this hook, line and sinker. They have tried to get God out of a bind, so to speak, because the Bible is in direct contradiction with the theory of evolution. People who take the Bible seriously and literally have introduced two theories to explain how the Bible and evolution can be reconciled. These theories are commonly known as the Gap Theory and the Day-Age Theory.Again, the above statement is typical of the majority view of the "informed" world of Christian theology and treats anyone who holds to the Gap Theory as being a child like uninformed Christian. It is further and again insinuated, that the theory was developed in order to reconcile the Bible and evolution. However, D. F. Payne, in his paper published by Tyndale Press entitled, "Genesis One Reconsidered", makes a brief statement which alludes to a different view than that of the majority: "The 'gap' theory itself, as a matter of exegesis, antedated the scientific challenge, but the latter gave it a new impetus". The right question to such a statement should have been, 'by how long did it antedate the scientific challenge, and how explicit are the earlier references.' Arthur C. Custance, rightly asserts in the book entitled "Without Form And Void." "If its antecedence can be established with any certainty, one then has to find some other reason than the threat of Geology for its having arisen".
It seems fair to state that if the Gap Theory was an accepted view held by earlier Christian commentators, it was presented without any intention of refuting a geological challenge to the veracity of the Holy Scriptures. It must therefore have arisen either because of a careful study of the original text of Scripture itself had given intimations of it, or perhaps due to some ancient tradition about the after-effects of the catastrophe itself. Why then has modern Christianity continued to assert that the Gap Theory is of modern origins? But, lest we get ahead of ourselves, let us continue our search backwards to find the true origin, if any, of the Gap Theory.
History records that during and after the Babylonian Captivity, the Jewish people began accumulating the comments and explanations of their best-known teachers of the Old Testament. These teachings were gathered together and are called the Midrash, the oldest pre-Christian exposition of the Old Testament. Louis Ginsberg, in his work entitled, "The Legends of the Jews," recorded this excerpt from the first chapter of Genesis:
from the Charis "Seminary" website
Jean