free your Church from sin
and protect it from evil.
Guide us, for we cannot be saved without you.
Oratio, Evening prayer, Liturgy of the hours (Christian prayer, p. 323); and Collecta, Roman missal (cf. CTS new daily missal, p. 1384, below), Monday, Third Week of Lent.
Something about that fourth line of the old English translation of the 1970s (now a hangover in the Liturgy of the hours) always takes my breath away, though it is an inaccurate rendition of the mid-8th-century, Gelasian-Sacramentary original (ed. Mohlberg (1960), no. 1218 on p. 181; Bruylants, vol. 2, no. 521; Corpus orationum no. 2418):
Ecclesiam tuam, Domine, miseratio continuata mundet et muniat, et, quia sine te non potest salva consístere, tuo semper munere gubernetur. Per.
Here is but one translation:
May thy continued mercy, O Lord, cleanse and defend thy Church; and because, without thee, she cannot keep safe, may she be always governed by thy gift. Through.
And here it is the 2010 English Missal (CTS new daily missal, p. 1384):
May your unfailing compassion, O Lord,cleanse and protect your Church,and, since without you she cannot stand secure, may she be always governed by your grace. Through.
It is there in the 1979 Book of common prayer, too, where it appears on pp. 180 and 232 as Proper 13:
O Lord, we beseech thee, let thy continual pity cleanse and defend thy Church, and, because it cannot continue in safety without they succor, preserve it evermore by thy help and goodness; through.
Let your continual mercy, O Lord, cleanse and defend your Church; and, because it cannot continue in safety without your help, protect and govern it always by your goodness; through.
In the earlier Books of common prayer and the Sarum missal (which adds the quæsumus) it is assigned to the 16th Sunday after Trinity:
[1549:] Lord, we beseche thee, let thy continual pitie clense and defende thy congregacion; and, because it cannot continue in safetie without thy succoure, preserue it euermore by thy helpe and goodnes.
[1662:] O Lord, we beseech thee, let thy continual pity cleanse and defend thy church; and because it cannot continue in safety without thy succour, preserve it evermore by thy help and goodness.(According to Hatchett, p. 190, the substitution of "church" for "congregacion" was an anti-Puritan move.)