They only heard (μονον ακουοντες ησαν). Periphrastic imperfect, "They were only hearing from time to time."

That once persecuted us (ο διωκων ημας ποτε). Present active articular participle, a sort of participle of antecedent time suggested by ποτε, "the one who used to persecute us once upon a time."

The faith (την πιστιν). Here used in the sense of "the gospel" as in Acts 6:7.