Where religion comes into it is from the very beginnings of the catastrophist philiosophy. Science in it's modern form where it is freely done without influence from religion really is only a relatively recent thing. Scientists (or philosophers as they were known) used to be persecuted, arrested and executed by the church. A lot of them were very religious themselves and attempted to find evidence that supported a more religious view of the world. Catastrophism is a failed line of science along these lines.
It's actually hard to find any scientific responses to Holden's claims, I think mainly because he is considered such a kook that it would only lower the integrity of actual scientists for them to get involved in debate with him.
Holden did once claim that he had found human skeletal fossil remains in carboniferous rock. He sent samples to the University of Calgary for testing and you can see a discussion of the results at the following link
Carboniferous human bones -- an evaluation
Of course Holden never admitted he got it wrong and probably still claims he has evidence of humans during the time of the dinosaurs. He is a creationist who has twisted science and resurrected an old branch of science that no longer has any validiy (a bit like say alchemy).
Basically there is nothing that Holden has written that you should take even slightly seriously.
If you want to read a relatively recent scientific paper on sauropods have a go at this
Biology of the sauropod dinosaurs: the evolution of gigantism - Sander - 2010 - Biological Reviews - Wiley Online Library