Why did God tell Ananias not to be afraid of Saul of Tarsus?
God had commissioned Saul of Tarsus as the Apostle of the Gentiles. Therefore Ananias did not need to fear Saul coming into his home. The Lord's instruction in Acts chapter 9 showed that Saul was divinely appointed for a specific mission to the Gentiles, so Ananias could receive him without fear.
Les explains that in Matthew 24 Jesus is speaking in His earthly ministry to the twelve about Daniel's abomination of desolation and the holy place in Jerusalem, as if these things could happen in their lifetime. Up until Paul, Scripture had Israel going out to the nations with the Gospel. But then God tells Ananias in Acts chapter 9 not to be afraid of Saul of Tarsus coming into his home, because God had commissioned Saul as the Apostle of the Gentiles. Les emphasizes what a difference this makes: Jesus was speaking as if all these things were about to happen, while Saul's commission marks a distinct turn to the Gentiles.