Kyrie, eleison is a Greek expression meaning "Lord, have mercy".
It's been used by Christians since the beginning, and it made its way into the Latin rite of mass, as in the priest (V) is speaking Latin and then he and the congregation (R) just switch to Greek with either Kyrie, eleison or Christe eleison:
V. Misereátur nostri omnípotens Deus, et, dimíssis peccátis nostris, perdúcat nos ad vitam ætérnam.
R. Amen.
V. Kýrie, eléison.
R. Kýrie, eléison.
V. Christe, eléison.
R. Christe, eléison.
V. Kýrie, eléison.
R. Kýrie, eléison.
This is the way the mass was said everywhere in Spain until barely 50 years ago and, in fact, there are some places where it is still said like that.
It is also used in many classical music pieces meant to be played during mass or just with a religious theme.
This is also the only case of a Greek expression I've been able to find in Spanish, and it doesn't even count because it is not used in common conversation.
However, Spanish is ripe with Latin expressions like vox populi, a priori, cum laude, per se, bis, mea culpa, ecce homo, etc. Some of them also have a religious origin.
Given that many Spanish words have Greek roots, I would expect at least a couple Greek expressions too, just like it happens with Latin.
Are there any Greek expressions in Spanish? And if there are none, why is that?