Let brotherly love continue. φιλαδελφία does not mean general philanthropy, but the peculiar love of Christians to each other as brethren; "a narrower sphere within the wider sphere of ἀγάπη" (Delitzsch); cf.
1. Peter Hebrews 2:17, "Honor all men, love the brotherhood;" and 2 Peter 1:7, where Christians are exhorted to add ἀγάπη to their φιλαδελπία. This grace of φιλαδελφία they had already, and had evinced it by their conduct (cf.
Hebrews 6:10, etc); they are only to take care that it court, me; and let them, among other ways, evince it in hospitality (2 Peter 1:2), and in sympathy with the afflicted brethren (2 Peter 1:3).