"Christianity is essentially a social religion... to turn it into a solitary one is to destroy it."
This is the fourth of Wesley’s thirteen sermons on Jesus’ Sermon on the Mount (Matthew chapters 5, 6, and 7). This sermon focuses on Matthew 5:13-16: "You are the salt of the earth... You are the light of the world... A city on a hill cannot be hidden... Let your light shine before others..."
Wesley says some brilliant stuff in this sermon. Much of it is a counter-argument against a movement in his day called "quietism," which taught that Christians only needed to worship God inwardly so as to avoid trusting too much in anything outward. Wesley never denies the importance of the inner aspects of our faith; in fact, he encourages ample time alone with God (at least two periods of solitude every day!). But he says that the inward roots have to produce outward branches in our lives with others, or else we cannot fulfill the kind of life that Jesus describes in the Sermon on the Mount.
Wesley begins this sermon by explaining the quotation above, that Christianity is essentially a social religion and to turn it into a solitary one is to destroy it. What he means by Christianity being a "social religion" is that it does not survive at all without "society" (which he describes as living and conversing with others; today we would be more likely to use the word "community"). He then describes the absurdity (also described by Jesus) of thinking that the light God has put into our souls can or should be hidden. Then he concludes the sermon by answering foreseen objections from critics.
Wesley is a master at holding together things which seem to be opposites, and finding a place of tremendous strength in hanging on to them both. This sermon is a great example of how he does this, in this case with "inward religion" and "outward religion." Christians of all groups would do well to dig into what he says here.
For further exploration of this sermon: