ANSWER: It is Aorist which, outside of the indicative and certain kinds of participles, is timeless and indicates a single completed act. Circumstantial Aorist participles denoting condition, concession, cause, or means, are always timeless. "Purifying," and "giving" in verse 8, denote means, thus: "And God bare them witness by giving (a single act, not a process) them the Holy Spirit * * * and he made no distinction between us and them by cleansing (a single act) their hearts by faith." See Goodwin's Greek Modes and Tenses, p. 49: "The Aorist Participle is sometimes joined with a verb of past time, to denote. that BY WHICH the action of the verb is performed, or that IN WHICH it consists: here it does not denote time past with reference to the leading verb, but rather coincides with it in time." Hence there is here no "evidence that they were purified prior to Pentecost." Wesley was too good a Greek lecturer in Oxford to make any such comment.
— Steele's Answers pp. 203, 204.