I have a quick question for you regarding Greek grammar. I have read that when an aorist verb tense is used in the indicative mood, it should be rendered as past tense in English. Is this always true? Specifically, I am thinking of Hebrews 10:5, where Christ says “a body hast thou prepared me.” Most major translations render “prepares” in the past tense. Is this a “slam dunk,” or could someone possibly argue that the verb could be future tense?
Yes, it is normally true that the aorist verb used in the indicative mood is rendered in a past tense in English focusing on action that was completed. However, it is not an absolute rule that always applies, only a general rule that would be valid in most cases.
As for Hebrews 10:5, the context fits better the past tense and not something that would be future. An aorist verb might refer to something present rather than something past, but it would be extremely rare for it to refer to something future and it would be only if the past or present does not make any sense.
So it should be kept in mind that if it is a quotation of the Old Testament which has different grammatical rules and the Classical Hebrew only had two tenses: perfect and imperfect. The former generally views the action complete and therefore translated as past in most cases. The latter emphasizes action is incomplete and therefore in most cases translated as future. The participles are usually translated as present tenses in English. The Hebrew would view this as a prophetic perfect, completed action yet in future time and then viewed as fulfilled in the Hebrews passage.