It sounds like you handled it as gracefully as one could. You told them you don’t agree but stopped short of trying to beat them into submission and it sounds like they also let it drop. I’d take that as a tacit agreement that we were “agreeing to disagree” on that subject and leave that particular stone unturned in the future. As to not liking to see unchecked ignorance, I understand what you mean. But, realistically, if they can dismiss all the evidence of evolution as “millions of years rubbish” you aren’t likely to shine new thoughts into their closed minds. Now if they bring up the subject again it is safe to assume that they have difficulty accepting that you have different beliefs. In that case I would say that the damage to the friendship has already been done.