Mora duit a Ghreen! The last suggestion you have there is the most accurate, i.e. "chun mórghlóire Dé". This has a bit of an old-fashioned ring to it, however, as in the modern language there's a tendency to avoid putting more than one definite noun in a row into the genitive case, but to keep all but the final definite noun in the nominative case with lenition. So a more modern-sounding version of this phrase would be "chun mhórghlóir Dé".