Gird thumbnail post

Hello everyone,
I'm new to the forum and theme. I was wondering if someone could help me implement Mathias thumbnail grid? I'm getting an error on line 12 of the template because I think the virtual theme is commenting out the php code. I'm not sure if the virtual theme is causing the conflict. If you guys have any other options similar to the Mathias design then I'll be happy to work with that as well. Thanks in advance.

Not sure if it is okay to link in this forum but here it is
https://gist.github.com/matthiaspabst/1959566

Here's a way to do it using the theme grid.