Same boat here, but with both my parents. They’re the utter poster children for Baby Boomers Gone Bad (sorry, all you Baby Boomers out there

). They’re both subscribers to the “if you’re a good person, you should get to go to Heaven” philosophy, but then, as they have no moral “north star” to point to what a “good person” is, they just wing it.
To top it off, my father is a history nut, and so he thinks that he’s an expert on the Inquisition, and that it proves that the Church is evil.

I have made it my mission this summer to do my own reading on the Inquisition so I can help him out a little.
I pray for them. They come to Mass with me if they have to. My mom has actually been asking questions here and there about the Church, and seemed open to my responses. She was most enthusiastic about how the people at my parish dressed in all manner of ways- up, down, jeans, suits, etc. In her mind, churches where everyone dresses up are bad, since God doesn’t care what you wear. I used that observation to point out that for Catholics, they come for the singular honor of receiving Our Lord in the Blessed Sacrament, and that everything else was secondary. Did I plant any seeds? Maybe. Maybe what you’re doing is planting seeds in your dad’s soul, too.
It’s like that song my Baby Boomer parents love so much (and, come to think of it, so do I) by Crosby, Stills, and Nash:
And you, of tender years,
Can’t know the fears that your elders grew by,
And so please help them with your youth,
They seek the truth before they can die.
Teach your parents well,
Their children’s hell will slowly go by,
And feed them on your dreams
The one they picked, the one you’ll know by.
Don’t you ever ask them why, if they told you, you would cry,
So just look at them and sigh and know they love you.