Summit
Highest point, top, apex, zenith, pinnacle, acme, culmination, utmost, maximum, climax, peak, crest, paramount, unparalleled, unequaled, unapproached, unsurpassed, superlative
The highest point toward which the work of the Church is directed is the liturgy.
Summit and Source (cont.) 
What does ‘summit’ mean?

Highest point, top, apex, zenith, pinnacle, acme, culmination, utmost, maximum, climax, peak, crest, paramount, unparalleled, unequaled, unapproached, unsurpassed, superlative

In other words, the highest point toward which the work of the Church is directed is the liturgy.