HCSB: "Above all, maintain an intense love for each other, since love covers a multitude of sins."
Peter Achtemeier (page 294) explains that the opening of verse 8 here likely reflects the language of verse 7, which mentions the "end of all things." Hence, πρὸ πάντων probably is a rhetorical turn of phrase that draws the reader's attention back to the previous verse, but more importantly, it emphasizes the importance and surpassing value of love--especially given the times.
Peter focuses on love for the Christian community (τὴν εἰς ἑαυτοὺς) but this does not mean a Christian can't love those outside of the local or universal ecclesia: Jesus taught that the second greatest command is to love one's neighbor and this does not seem to be limited to one's Christian brother or sister.
Achtemeier connects 1 Peter 4:8 with 1 Peter 1:22, which uses the adverbial expression "love one another intensely." By employing the words, ἀγάπην ἐκτενῆ ἔχοντες, Peter refers to the act of loving one's spiritual siblings fervently. Ceslas Spicq thinks Peter is referring to intensive love that Christians should have for one another. WT publications often have pointed to the meaning "outstretched" for the adjective ἐκτενῆ in 1 Peter 4:8 and the definition "outstretchedly" for 1 Peter 1:22. The act of stretching out fabric has been utilized to illustrate this concept.
BDAG Entry: ἐκτενής, ές ⟦ektenḗs⟧ (Aeschyl.; Polyb. 22, 5, 4; ins [s. on ἐκτένεια]; PTebt 24, 45; 3 Macc 3:10; 5:29; Philo; Just., D. 107, 2 ἐκτενοῦς ὀλολυγμοῦ) pert. to being persevering, with implication that one does not waver in one’s display of interest or devotion, eager, earnest, comp. ἐκτενέστερος (IGR IV, 293 II, 38) Ac 12:5 v.l. ἐκτενῆ τὴν δέησιν ποιεῖσθαι make earnest supplication 1 Cl 59:2 (UPZ 110, 46 [164 b.c.] τὴν ἐκτενεστάτην ποιήσασθαι πρόνοιαν). ἐκτενῆ ὑπὸ πάντων προσευχὴν γενέσθαι AcPl Ha 6, 6f. τὴν ἀγάπην ἐκτενῆ ἔχειν keep affection constant 1 Pt 4:8. μετ’ ἐκτενοῦς ἐπιεικείας w. constant gentleness 1 Cl 58:2; 62:2.—DELG s.v. τανυ- etc. E p. 1092. M-M. TW. Spicq.
Ralph Earle (Word Meanings in the New Testament): Fervent This English adjective is defined as: “Having or showing great emotion or warmth” (American Heritage Dictionary, 485). But the Greek word here, ektenēs (only here in NT) has a somewhat different connotation. It comes from the verb ekteinō, “stretch out”; so it literally means “stretched out.” C. E. B. Cranfield says that it “suggests rather the taut muscle of strenuous and
sustained effort, as of an athlete” (First Epistle of Peter, p. 95). A good translation is “unfailing” (RSV).
Reference: Achtemeier, Paul J. 1 Peter. Hermeneia – A Critical and Historical Commentary on the Bible. Minneapolis: Fortress Press, 1996.
