How do you say hallelujah in Irish Gaelic?

There isn't a direct, single-word translation of "Hallelujah" in Irish Gaelic that captures the same religious connotation. "Hallelujah" is a Hebrew word. You would need to translate the meaning, which is something along the lines of "Praise ye the Lord."

You could use phrases like:

* Molaimid an Tiarna! (We praise the Lord!) - This is a fairly direct and common way to express the sentiment.

* A bhuíochas le Dia! (Thanks be to God!) - This emphasizes gratitude to God.

* Glóir do Dhia! (Glory to God!) - This focuses on the glory of God.

The best choice depends on the specific context. None of these are exact equivalents, but they convey the spirit of "Hallelujah."