The bad "creationism" of the 19th century unfortunately gave an excuse for the idea of evolution

Here is a letter by Wallace to the British Quarterly about controversy being raised over Darwin's theory. What interested me in particular was his remark in the first paragraph that shows that the standard "creationist" understanding of the day was very far from a Biblical understanding.  They asserted that God created AGAIN AND AGAIN, though the Bible is clear that God RESTED after creating all things.

The 'British Quarterly' and Darwin (S107: 1865)

   [[p. 77]] Allow me to call the attention of your readers to a very gross attempt, in the last number of the British Quarterly Review, to mislead the unscientific public. At p. 143, in an article on the 'Supernatural,' after disposing of Hume, Strauss, Baden Powell, and such small fry, in a few lines each, the reviewer claims physical science as his ally, and calls into the witness-box 'the geologist' (one of a type now happily almost extinct), who, he says, will tell us that again and again the special interference of a Creator has been required, and who finally 'will tell you that this same "development" or "origin of species by natural selection" is an unblushing intruder into the domain of science, unlicensed and unrecognized.'

Darwin commented on this wrong creationist thinking in his Origin of Species, which I mention in a post about Darwin a while back.  This is unbiblical and it needed to be criticized and overthrown, for which we could even thank Darwin since it forced Christians back to the Bible.  Darwin of course didn't criticize it as unbiblical, nor does Wallace here, but that is what was wrong with it. 

If the creationists had been true to the Bible it might have been possible to prevent the theory of evolution from ever happening!

It is certainly true that the forces of evil are going to treat Christianity as inferior anyway, but in this case it's pretty clear that such unbiblical approaches to science did give them an excuse. I don't know if the liberalizing influences had simply undermined Biblical doctrine to such an extent or what.

It's sad to read the rest of that letter Wallace wrote because he just goes on and on about the stupidity of another witness they were able to muster for the "creationist" side:

This, however, is not strong enough. The model 'geologist' is sent down, and a new witness is specially called in a note, which is so 'unblushing' that I give it entire.

'Let us hear a word on the subject of development from one who has won scientific laurels by a life of study and thought:--"All the great living and recently deceased masters of physical science reject it. Does it appeal to anatomy and physiology? Cuvier, Owen, and Carpenter cry out against it. Does it evoke the aid of chemistry? Berzelius, Turner, and Liebig see its shallowness. Does it call on zoology for aid? Agassiz and Ehrenberg can refute its claims. Does it search the archives of geology for support? Sedgwick, Miller, Lyell and D'Orbigny can show how certainly it will fail. Or, finally, does it appeal to botany? Hooker and Lindley, Torrey and Gray, know that it will certainly glean nothing to sustain it in that flowery field. The fact is that it is only here and there a second-rate naturalist will sympathize at all with such dreamy views." (Dr. E. Hitchcock, in "Bibliotheca Sacra," vol. xi. p. 789.) We do not think anything in this extract unwarranted, even though Mr. Darwin has added his name to the roll of non-theistic theorists; for though he is distinguished as a naturalist in the department of [[p. 78]] observation, his book exhibits philosophic abilities of the lowest order. Nothing can be more significant than his entire abandonment of geology; nothing more foolish than the supposition that some strata are so lost that no trace of them can be found; and nothing more unscientific than to help his theory to take its absurd shape out of the barely possible but utterly unknown.'

Either the writer of this article knew that at least four of the persons here mentioned--Carpenter, Lyell, J. Hooker, and A. Gray--so far from rejecting or crying out against 'development' and 'the origin of species by natural selection' are its strongest supporters, or he did not know it. He is, therefore, either imposing a deliberate and wilful misstatement on the public, or he is incredibly ignorant of the subject he is writing upon. Again, when he talks of Darwin's 'entire abandonment of geology,' does he know that almost all the great modern geologists are converts to his views? and when he stigmatizes Darwin's work as 'foolish' and 'absurd,' does he know that John Stuart Mill has adduced it as one of the most wonderful examples of logical reasoning extant?

It is hardly worth while to break such a fly upon the wheel, but it is well to make known as widely as possible to what weak subterfuges those who attempt to stem the flood of modern thought with the worn-out theological mop are at last driven.

At the very least can it be said that the abandonment of an aggressive BIBLICAL creationist argument, along with abandonment of scholarship in general by Christians, gave license to this sort of attack?

I think so, and I also think this same abandonment of Biblical creationism and general ignorance of the scientific context are all too apparent these days as well. In fact you may get called all sorts of names by Christians for simply trying to keep up with these things at all.  

The weakness and irrelevance of creationism today is demonstrated all too clearly at the debate forum, EvC, or Evolution versus Creationism, where the "creationists" are a sad and sorry lot of misinformed people, and many of them argue from wildly unbiblical positions.  Very few hold to the Biblical Young Earth position (earth around 6000 years old), hardly two of them agree with each other about anything at all, and the few who do seem to be truly biblical creationists who also know their science get into such technical areas of discussion the average Christian couldn't possibly follow their arguments anyway.  I know I can't.