Stephen quotes from Amos 5:25–27. In his quotation he makes use of the Septuagint which has some slight differences to the Masoretic text (used by most modern English Bible translations). Moloch was the god of the sky and the sun to whom some brought child sacrifices, and Rephan was possibly the name of an Egyptian god associated with Saturn.1 Stephen’s quotation is meant to show that rejection of God’s servants is something which has happened again and again.
42 But God turned away and gave them over to worship the host of heaven, as it is written in the book of the prophets: “‘Did you bring to me slain beasts and sacrifices, during the forty years in the wilderness, O house of Israel?