What does Acts 7:48 mean?

At the time of Jesus, and Stephen's speech, Herod's temple sat on top of the Temple Mount. About forty years before, Herod the Great had decided to renovate the temple Zerubbabel had led the Jews to build upon their return from Babylon (Ezra 1:2). It was he who placed the huge blocks of stone and infilled the land to make the top of the temple mount so large and flat. Although Herod the Great was not a good man, the Jews were proud of their temple and very protective.

What they had forgotten was something Solomon had said upon the building of the first temple: "But will God indeed dwell on the earth? Behold, heaven and the highest heaven cannot contain you; how much less this house that I have built!" (1 Kings 8:27). God proved him right: "As soon as Solomon finished his prayer, fire came down from heaven and consumed the burnt offering and the sacrifices, and the glory of the LORD filled the temple. And the priests could not enter the house of the LORD, because the glory of the LORD filled the LORD'S house" (2 Chronicles 7:1–2).

Stephen understands his accusers' love of the temple. He is also a Jew, though a Hellenist who lived far from Jerusalem. Most likely, like them, he had traveled to Jerusalem to worship at the temple. But when he arrived, he found out about Jesus. And he knows that Moses, the Law, and the temple are nothing compared to worshiping the Son of God.

Jesus had explained this to a Samaritan woman a few years before. She asked Him if her people were right to worship on the local mountain, or if they should worship in Jerusalem (John 4:19–20). Jesus responded that, a time was coming when people no longer be obligated to worship at the temple. Instead, they would worship wherever they were, in spirit and in truth (John 4:21–24). The attitude of worship and the object of worship matter, not the location.