John 8:31

Which had believed him

(τους πεπιστευκοτας αυτω). Articular perfect active participle of πιστευω with dative αυτω (trusted him) rather than εις αυτον (on him) in verse John 8:30. They believed him (cf. John 6:30) as to his claims to being the Messiah with their own interpretation (John 6:15), but they did not commit themselves to him and may represent only one element of those in verse John 8:30, but see John 2:23 for πιστευω εις there.If ye abide in my word

(εαν υμεις μεινητε εν τω λογω τω εμω). Third-class condition with εαν and first aorist (constative) active subjunctive.Are ye truly my disciples

(αληθως μαθητα μου εστε). Your future loyalty to my teaching will prove the reality of your present profession. So the conclusion of this future condition is put in the present tense. As then, so now. We accept church members on profession of trust in Christ. Continuance in the word (teaching) proves the sincerity or insincerity of the profession. It is the acid test of life.