Matthew 24 is for the future Tribulation period. Ephesians 2:8-9 is for today.
Mid-Acts Hyper-Dispensationalists try to make Paul's conversion (Acts 9) the dividing line between two completely different dispensations. But the Bible has dispensational "overlaps" and gradual doctrinal transitions between Jesus' birth and the completion of the New Testament. The Mosaic Law was technically still in effect until the crucifixion (Luke 10:26, Matthew 23:23, 27:51, Colossians 2:14, Hebrews 9:17), and yet forgiveness of sins by faith was given by Jesus as far back as Mark 2:5, and salvation by faith alone was offered as presently available as far back as John 3:36. (See also John 5:24, 6:47, Luke 7:48-50 and 8:12). But believers were not put into the body of Christ until Acts 2:4 (compare Acts 1:5 and 1 Corinthians 12:13). As far as is recorded, the first convert to understand and believe in Jesus' blood atonement was in Acts 8:32-37 (before Paul was saved), and Paul himself led people to Christ WITHOUT preaching the atonement in Acts 13:16-43.
I\m a King James Bible believing, moderately dispensational, Pre-Trib, independent Baptist Christian.