Comment:  When Christians gather, they feast on the word of God, exhort one another, and learn from one another.  They practicalise the bond of Christian fellowship by the love they show to one another. But some are not sincere in their profession of the faith. They  are selfish and are out for their own personal interests, not to share what God has provided with others.  Their interest is not to build others’ faith and thereby strengthen their own. They are spots in the feasts of charity among Christians.  We should serve God with faith and understanding, that is, with diligence and sincerity,  so as not appear pious before people whereas the opposite is the case.  St. Peter  in his general epistle explains the text further “… Spots they are and blemishes, sporting themselves with their own deceivings while they feast with you; Having eyes full of adultery, and that cannot cease from sin; beguiling unstable souls: an heart they have exercised with covetous practices; cursed children.” (2 Peter 2:13-14) Our Lord Jesus Christ stated “Ye are the salt of the earth: but if the salt have lost his savour, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men.” (Matthew 5:13) Yes such ones are  “Raging waves of the sea, foaming out their own shame; wandering stars, to whom is reserved the blackness of darkness for ever.” – Jude 1:13.