Is the church age specifically indicated anywhere in the Old Testament, the Gospels, or the book of Acts?
The church age is not specifically indicated anywhere in the Old Testament, the Gospels, or the book of Acts. Jesus knew it from His deity, but He never revealed it; Peter did not understand it either. The context states no hint of this age appears in those portions.
Les explains that Jesus' answer in Acts 1:7 affirmed the kingdom was coming and the twelve tribes would be ruled, but the times and seasons were in the Father's power. Les emphasizes that never in the Old Testament, the Gospels, or even in Acts is there a specific indication of the church age. Jesus knew from His deity that Israel would be dispersed and He would turn to the Gentiles, but He never indicated it. Peter also did not catch on; he expected God to fulfill Israel's promises shortly. So there is not a hint of the last 1,900 and some years, the church age.