There was most certainly an element of truth in their claims. Most likely Stephen had been saying that the coming of Jesus Christ has resulted in a change in terms of the customs handed out by Moses which served to mark the Jews as a separate people. He would have highlighted the fact that Jesus has come to fulfill the law (Matthew 5:17). When it came to the temple, Stephen would have also mentioned the changes that had come as a result of the new covenant inaugurated by Jesus.1 Specifically, the fact that one can worship God anywhere and that worship is not limited to houses built by men (Acts 7:48–49).2
14 for we have heard him say that this Jesus of Nazareth will destroy this place and will change the customs that Moses delivered to us.”