A.F.
You AND your hubby need to sit down with them and detail what things they cannot say. Make a list so you don't forget anything. I don't care if they are 150 years old, they still have power over their tongues. My in-laws do this occasionally (thankfully not racist or homophobic or anything as damaging our kids self esteem) with lewd, sexual comments, dirty jokes, talking about other people in a bad light, horrible language, etc. and we stop them as they are saying it. And you know what? They are GRACIOUS about it and don't want to do those things in front of the kids. They actually thank us for reminding them to watch their tongues.
Your inlaws don't seem to know much about honoring. As far as being Christians.......tell them to act like Christian's ought to act. Tell them to open their Bibles to the book of James to see what it means to tame the tongue.
Don't feel like you have to sit idly by or even rely on your husband to talk to them. You can stop them AS they are talking and say that it's time to change the subject because little ears are listening. They will get mad.....it's a given. But who cares? The right to free speech comes with responsibilities and you and your husband can hold them accountable when they are around your kids.
GOOD LUCK!