"[T]hey will know we are Christians..." is a line from a song, paraphrasing Tertullian, not a verse from the Bible.  

More than a call to Charity, the Gospel message is a call to repentance.  The mass, even without a homily, even done by an unworthy sinner like the priest, even without receiving communion remains the primary way in which we, as Catholics, express the virtue of Religion.  If one believes in a God, One Who created us from nothing but for mere love, one has a duty to offer Him praise.  Raised in the faith, a Catholic understands that individual praise is laudable but that the mass is a different level of prayer.

Individual churches - their priest(s) and community of believers or the actions of wicked men and their enablers (whether intentional or no) - may not offer everything we might hope for, but this does not obviate a responsibility to God and to ourselves to practice the faith as it has been handed on.  "Commitment to the faith" - doubt is no excuse.