The term "spiritual" is a strange one, since even some agnostics are happy to apply it to their sense of wonder at the world. By some definitions, Richard Dawkins might even be described as "spiritual", just as the agnostic Albert Einstein was. Seamus Heaney is one of the most "spiritual" poets one could find, but he, too, tells us he is agnostic on the existence of God.
This is worth noting because it would appear that the people of Ireland have just elected the least institutionally-religious of the available candidates for president. That may tell us something about the current cultural mood in Ireland. Or it may simply tell us that they made a last-minute dash away from Sean Gallagher.
In any case, Michael D Higgins will have to use some explicitly religious language when he takes the oath of office. A constitutional convention is due to review the wording of the oath next year (along with other proposed reforms), and the new president has already signalled his support for a change to more inclusive terms. But when he steps up to take the oath, Michael D will be asked to invite the help of a Being whose existence he may privately question.
The oath reads (Article 12.8):
"In the presence of Almighty God, I ... do solemnly and sincerely promise and declare that I will maintain the Constitution of Ireland and uphold its laws, that I will fulfil my duties faithfully and conscientiously in accordance with the Constitution and the law, and that I will dedicate my abilities to the service and welfare of the people of Ireland. May God direct and sustain me."