Hello all, new user today. Mostly looking to get a bit of friendly advice and hoping someone else out there has experienced a similar issue to mine and has come through it unscathed.
I’ll try to keep this as brief as I can;
My brother and I have always been atheist. Always had the skills of knowing ‘how’ to think, rather than what to think. Or so I thought.
My brother has recently (within the last 2yrs) become a heavily influenced Christian. Heavily. He met some girl, fell in love, drank in the hormonal effects of a new relationship and has adopted her very strong belief system. It was a shame really because I lost one very important outlet for rational conversation as my wife doesn’t care much for indulgence for beliefs she doesn’t care about either direction.
My father moved across the country from us 20 years ago. My brother had very little conversation with him until he “found the glory of God”, however I have maintained a pretty good relationship with our Dad, who very recently received a large settlement from the VA for a 30 year old medical claim. He purchased a plot of land, and made himself comfortable for the short time he has left.
Immediately following this event, my newly converted brother and his new wife (who is evidently 100% disabled and receiving compensation for both herself and my brother) packed up all their belongings, and moved in to a house down the road from my Dad.
Following several apologies and visits, they are now working on a full on conversion of my father and from what I can tell, fixing it to alienate me and my wife and kids from his life.

My questions are these: is there anything I can do? If so, what? If not, how do I compartmentalixe this so it isn’t bothering me so much.
If my brother and wife are successful they will have pushed away me, my Dads girlfriend, and will move in to his place, eventually killing him in the most parasitic way possible.