[MarMema]

Thank you!
It is an icon of Christ's resurrection.
Someone else will come and do a better job of detailing it, but until then I may be correct about a few things.
Christ is shown having risen from Hades, the brass gates of Hades are at his feet, broken and destroyed.
I think the two figures at each side in red and green represent Adam and Eve, and I believe Christ is depicted as pulling them from their tombs.

[drstevej]

Interesting, thanks.