On the Trisagion found in the Syrian Rite

From The Ebb and Flow of Consciousness...

'Holy God, Holy Mighty, Holy Immortal, who was crucified for us, have mercy on us.'

In his "Syrian Rite" volume Archdale King spends much time comparing liturgical practices of the "Jacobites", Maronites, and Syrian Catholics but he makes scant reference to Eastern Orthodox. (Maybe he spends more time on this in the "Byzantine" volume?) He does make mention a Syriac alteration to the Trisagion: "who was crucified for us" (destlebt hlofeyn), which evidently expressed enough of a wrong theological conclusion that it caused riots. If the Orthodox Antiochian church was using an earlier Liturgy of St. James, they were at least cognizant of theological subtleties. This added phrase remains in the Syriac Trisagion btw.

The Syriac liturgy does use a lot of Greek. In the cycle of Syriac prayers, Lord have Mercy is rendered in both Syriac and Greek, but it seems to be repeated more often in Syriac, at least in the daily prayers. I see no problem with using Syriac as long as its a natural extension of the parish. For example, there is a Russian priest in Jerusalem that sometimes uses the Turoyo dialect. We've had a few syriac-knowledgeable Eastern Orthodox folks from Syria pass through our parish over the years too.

Despite this, and despite the fact it has been used for centuries in the Orthodox Church, some would see any Syriac use as 'suspect' or not organic enough. But in our Syrian/Anglo parish, there we stand singing Lord Have Mercy in Arabic, Greek, and Swahili.

And from New Advent...

... just before the lessons the Trisagion is sung. That of the Greek rite is: "Holy God, holy Strong one, holy Immortal one, have mercy on us." The Syriac rite adds after "holy Immortal one" the words: "who wast crucified for us." This is the addition made by Peter the Dyer (gnapheús, fullos) Monophysite Patriarch of Antioch (458-471), which seemed to the Orthodox to conceal Monophysite heresy and which was adopted by the Jacobites as a kind of proclamation of their faith