“And what concern is that to us?” you say. The greatest possible concern if you pay no attention to your brethren, if you do not exhort and advise, if you put no constraint on them, and do not forcibly drag them hither and lead them away out of their deep indolence. For that one ought not to be useful to himself alone, but also to many others, Christ declared plainly when He called us salt and leaven and light: for these things are useful and profitable to others.
For a lamp does not shine for itself, but for those who are sitting in darkness: and you are a lamp not that you may enjoy the light by yourself, but that you may bring back yonder man who has gone astray. For what profit is a lamp if it does not give light to him who sits in darkness? And what profit is a Christian when he benefits no one, neither leads anyone back to virtue?
Saint John Chrysostom
If Thine Enemy Hunger, Feed Him
Homilies on Profitable Subjects