"We are scared."
Translation:Tha an t-eagal oirnn.
Not in the way where one is derived from the other: eaglais is a borrowing from Latin ecclēsia (in turn from Greek ἐκκλησία, cf. ecclesiastic), whereas eagal is most likely derived within Goidelic from gal "valour" with the compound form ess- of the preposition meaning "out of" > "without" (cf. ScG à/às).
So the only etymological connection between eagal and eaglais would be that, purely by chance, they both contain the Indo-European preposition that is found in Old Irish ess- (in compounds, otherwise a), in Greek ἐκ/ἐξ, and also in Latin ex.