Pushing religion acceptable?

My inlaws have joined a very conservative church and everytime we are together they bring up religion. We have told them that we don't want to discuss the topic, we don't agree with their views, but they still find ways to bring it up, including trying to give us books on the subject. I've said we need to avoid them all together....is this a good idea? We do have kids and we still want them to see their grandparents. However, they show no interest in our kids, since they have other grandkids that share their religious views. (They have forgotten our kids birthdays as an example)