filatdav on "500 server error after migrating to CentOS 7 --only homepage"

Hi,
I've struggled for the last few days to migrate my blog from bluehost to a CentOS 7 VM instance on Google Cloud Compute Engine, but I've encountered a great problem. The wp-admin dashboard is working perfectly, yet the homepage or any other post page isn't working but displaying a 500 server error: 'Failed to load resource: the server responded with a status of 500 (Inteal Server Error)'. I've used a few advices from the inteet and I came to the conclusion that it is a theme problem. Can you help me with this and suggest any fix, please!

You may check my site adding this string to your hosts file:
130.211.63.172 moldovacrestina.md

Or, if you want to see the working version of the site, check moldovacrestina.md before changing the hosts file. Thank you!

I've used a few advices from the inteet and I came to the conclusion that it is a theme problem.

Does your site work properly under the Twenty Sixteen or Twenty Fifteen themes? If so, what is the name of the theme with the problem, and where did you get it from?

Yes, the site is working perfectly with the default theme. The problem is that the theme is customized for the site contents, so we can't use any other theme. You can download the theme here, but I would appreciate if you won't share it nowhere. Thank you!