For me what’s actually turned out to be the best approach is to help them see the Bible in a better light. They believe in creationism not because of scientific evidence, but faith that the word is meant to be taken literally in genesis concerning human origins and so on.
I show them the literary techniques used by the authors to create a story. Such as what Abel’s name is, what Cain’s name is, how we know that earth is not flat and wrapped in a dome, and bring up issues of contention such as if Adam was immortal, then why was there a tree of life that sustained eternal life. I bring up the differences between the two creation accounts side by side. I talk about why is it that the actions Eve accuses the serpent of in Hebrew is the same sound serpents make, hiss, in how it sounded. I bring up issues such as in Joshua where it says the sun revolves around earth and how we know that’s not true.
Then I begin to attack their misguided belief about the Bible itself. Such as where in scripture do we find evidence that a council of men had a right to decide what was in scripture. There is no supporting verse for that. I bring up bow throughout the world at various times there was multitude of books considered true and throughout the shes they’ve changed. I ask them why is it in Jude that it’s mentioned Moses’s corpse was argued over by Satan and Michael , and why does Jude mention the prophecies of Enoch when neither of those stories are in the Torah. The books that have historically contained those stories were rejected from canonization. So was Jude wrong, was the council wrong, is there different books here that was not the same then and so on. I bring up the book of Jasher and missing letters of paul by references to them found in scripture and ask why is it that our bibles don’t contain every book that it mentions itself.
After a few bible studies focused on this, I find many begin to doubt the false esteem they held scripture in. Not that the word is a lie or false, but that they almost set the word up as a god itself and that they needed to readjust their understanding of it. In my experience when they begin to change their view on how perfect the Bible is, they begin to be more open to ideas that perhaps scripture is not meant to be taken literal in genesis based on the Bible itself. After that, they become more open to a scientific explanation of creation because it’s no longer science vs Bible, but science vs one faulty interpretation of the Bible. It helps undermine that false war they created by demanding literal interpretation.