I argued in a previous post that God needs to develop living creatures by means of a continuity of physical forms, so evolution must proceed by means of descent by modification. This phrase is often taken to define Darwin’s theory of natural selection, to distinguish his theory from that of immediate, special and separate creations. Now, however, different terminology is needed. Since Darwin thought of his theory as natural selection, let us describe ours as containing theistic selection. Where he talked about survival of the fittest, we agree, as long as we do not forget that fitness also depends on reception of life from God, a reception that also depends on our organic structures. Thus, in theistic selection, we have also a survival according to reception. We are talking here only about what factors influence the survival of plants or animals in the world. We especially mean those that are in addition to physical and ecological factors already known. Theistic selection must include all the considerations of natural selection as well since the natural or physical degree is an essential part of our theistic structure.
The details of the causes and means of modifications remain an open question within theistic science. Two limiting cases for these causes can be called the ‘hands on’ and ‘hands off’ treatments by God. The hands-off case is when the only sources of modifications are random mutations, genetic drift and genetic recombinations during reproduction, just as in present-day neo-Darwinism. That is, God would wait for suitable new forms of organisms to naturally arise, and then the degree to which these new organisms are physically, mentally and perhaps spiritually fit will mean that they live longer and be more likely to reproduce. There is therefore both natural and theistic selection, but the actual origin of the species is explained in the same way as by contemporary evolutionary theory.
According to the ‘hands off’ explanatory theory, we would see why the forms of organisms are not arbitrary. The theistic component of the selection process means that creatures who are able to successfully receive and retain life from God are more likely to survive and hence to reproduce. Over the long term, organisms that have the human form will tend to be produced because they will be favored numerically in any competition for limited resources or (say) in resistance to diseases. Their mental perceptions and thoughts will more accurately portray reality. This hands-off view is one kind of theistic evolution. Let us call it theistically-filtered evolution to distinguish it from the common view of ‘theistic evolution’ wherein God does not have any kind of causal or filtering role in evolution at all.
The other limiting case is that of ‘hands on’ management by God. In this limit, God is continually involved in the day-to-day influx of divine life and hence also in the long-term management of genetic and physiological structures. That is, God would be not infrequently be producing modifications to the molecular structures of organisms, but in such a way that this is not directly noticed by the creature. The creature is never deprived of its sense of living as if from itself.This is a fundamental requirement for all life on earth, with the result that any new modifications must in some way be hidden from having immediate effects, at least until the being develops new loves that want and correspond to the new molecular structures. We could call this limit theistically-driven evolution. We should expect some ‘driven nature’ of evolution if we think that God has a particular interest in or desire concerning its result. In the ‘fully driven’ limit, which we might expect if God is completely benevolent, unselfish, and diligent in wanting us to develop, God will be doing everything possible to manage the detailed generation of genetics, species, and ecologies to accomplish first what is good and later what is very good.
All of these kinds of theistic evolution imply that the actual causes of evolution are internal. If we watch evolution in progress, we always see continuous changes in living organisms. And even if we could examine the physical and molecular structures of the organisms during that evolution, we would still only see continuous paths of the molecules. There is never any ‘popping into physical existence’ of a new creature or species where there had been empty space. Neither is there any sudden creation of new creatures ‘out of dust’. Even the very simplest bacterium has a complex internal structure that must already correspond to some simple mental sub-degree and therefore cannot be created immediately by God. Otherwise the non-physical sub-degree would be missing its ‘skin’ of previous historical actions as the basis for that bacterium’s independent life. This necessary physical continuity what is meant by ‘descent by modification’, by gradual modification. Descent by modification, we conclude, cannot be used to characterize Darwinism or neo-Darwinism, since now we see that it is a necessary component of any theory of evolution within theism.
We may think of theistically-driven evolution as intelligent design since God is intelligent and God is continually working on and modifying species. However, it is certainly not part of the ‘design and build’ procedure as we know it in, say, engineering. God is always working with existing biological creatures and doing the best that is possible to pull creatures into life, always according to knowledge of the physical structures that will successfully receive and retain their mental and spiritual life. Patience is clearly needed. Sometimes beings, once developed, are invaded or eaten by others (infection and predation) if that helps the function of the overall ecology though perhaps not some of the individual beings. The requirement of physical continuity means that the beings possible within a given time scale have genetic or epigenetic (in the cell, but not part of the genome) relics from previous creatures whose genes were modified to make the present creature. This must happen often since no creature is a creation ab initio. There is always a development from what already exists towards what is desired in the future.
For more details, see the book "Starting Science From God"