Leave it as "exp".

仏ほっとけ神構うな	No matches
仏ほっとけ神かまうな	No matches
12 hits on twitter this side of 2018 (including some variations like 神は構うな、仏ほっとけ but mostly ad verbum)
現代言語研究会の故事ことわざの辞典 
http://www.jlogos.com/d005/5552565.html
"神や仏を信仰するのはよいが、深入りすると、かえって精神が乱れることさえあるので、ほどほどにしておくのがよい。
※「ことわざ小辞典」より
なんだか駄洒落みたいな諺ですが、ちゃんと辞典に載ってます。"
http://www.imacoco.me/entry/2016/08/17/143533

I'm not sure it's really a proverb (like some of the sources say) or simply just a ダジャレ. 
I initially read this as:
"back off Budda, go away gods"
but a native informant thought the other reading was more likely. I wouldn't be surprised if it were used in both 
ways.