Whosoever shall confess (hos ean homologēsēi). Indefinite relative clause with modal ean (= an) and the first aorist active subjunctive, “whoever confesses.” See 1Jo 2:23; 1Jo 4:2. for homologeō.
That (hoti). Object clause (indirect assertion) after homologeō. This confession of the deity of Jesus Christ implies surrender and obedience also, not mere lip service (cf. 1Co 12:3; Rom 10:6-12). This confession is proof (if genuine) of the fellowship with God (1Jo 1:3.; 1Jo 3:24).