(B) Whose sins are referred to in V25 as the sins that are past?
(B) Whose sins are referred to in V25 as the sins that are past?
(cp V25). These are the sins of all those who lived in Old Testament times before the atoning death of Christ.
God merely suspended judgement for their sins until the price for them was actually paid by Jesus (cp Ac 17:30-31; He 9:15; 1Jn 2:2).
As New Testament believers look back on the cross for their redemption, so the Old Testament saints looked forward to the cross for their redemption.
Everyone who took part in the sacrificial system under the old covenant was vindicated by the sacrificial death of Jesus under the new covenant (cp He 9:16-28).
Even Abel made a sacrificial offering to God which pointed to the future redeemer (cp Gen 4:1-4).
See also comments on Ro 4:1-5; He 9:15; 10:5-7 and 10:14