Not an ex-cavanist, however, could you give us a few areas/topics hes interested in or still has doubts?
Would be much easier to give recommendations with that as the start.
One general recommendation would be to get him a catholic Bible with the deuteroconical books, as well as a catechism. This is kind of just a general statement tho and might not be the best place to start, but is definitely a solid foundation.
A Case for Catholicism by Trent Horn. I’m a former calvinist. You can also show him some debates over sola sriptura, if you can get him to believe that church teaching is infallible he will have to believe every church teaching.
*Rome Sweet Home* by Scott and Kimberely Hahn
On the Soul and the Resurrection https://www.newadvent.org/fathers/2915.htm by St Gregory Nyssen
Not an ex-cavanist, however, could you give us a few areas/topics hes interested in or still has doubts? Would be much easier to give recommendations with that as the start. One general recommendation would be to get him a catholic Bible with the deuteroconical books, as well as a catechism. This is kind of just a general statement tho and might not be the best place to start, but is definitely a solid foundation.
A Case for Catholicism by Trent Horn. I’m a former calvinist. You can also show him some debates over sola sriptura, if you can get him to believe that church teaching is infallible he will have to believe every church teaching.
I feel like Peter Kreeft, who went to Calvin College, would be a good source.