Just for the record, I count myself a Christian. Scientists are too nice. We hope that logic and truth will overcome blind prejudice and fanatical bigotry. The confused and largely ignorant world wants sound-bite politics so that it can whoop and cheer when a point is scored. It does not want to be convinced of the rightness or soundness of anything.
Scientists are hopelessly wrong in trying to counter the mad viewpoint of creationism by reason.
If the Bible is literally true then if even one word of it can be shown to be wrong or in doubt, the whole edifice of fundamentalism is weakened. Ask creationists to justify and explain the manifold and manifest inconsistencies of the Bible. Ask them to reconcile a hundred years of biblical and scriptural analysis and investigation that has shown that the history of Palestine and the regions around are utterly unlike the apparent histories of the Bible. Instead of trying to counter the pseudo-scientific distortions and manipulations of the creationists, go for their weakest and most vulnerable points. Ask them if they have ever considered that the Bible may not be what they take it for.