For some (like my BIL who taught CCD) had an emotional “born again” experience which pulls them away from the True Faith. And to justify their leaving, feel it necessary to attack their former faith.
Most people (not all though), leave the faith Not for doctrinal or theological reasons, but personal reasons like an emotional experience or a disagreement with Church teachings.
As a convert, I can tell you that not all practicing Catholics really understand the basis of the faith. I can remember many times asking questions while going through RCIA only to hear, “I don’t know, that is just how we have always done things”.
Try sitting down with them and discuss the reasons why they are in their new faith community. Not in a judgmental way, but truly to understand their reasons. Keep in mind though, that some of the “born again” faiths are very persuasive and have a strong influence on their members.
In the end though, you may simply have to tell them that they are invited but the wedding WILL go on as planned and that you and your partner have invited GOD to be the Center of your marriage.
Amazing how hearts may change once the grandchildren start coming:thumbsup: