Question: "What does the Bible say about selling in church?"
Answer: The first Scriptures that come to mind in regard to selling in the church are Matthew 21:12-13, Mark 11:15-17, Luke 19:45-46, and John 2:13–17, all of which describe the incidents (there were two) when Jesus "cleansed" the temple. When He saw the kinds of activities that were being carried on in His Father's house, He became very angry. Clearly, this was not what the temple was built for.
Jesus regarded both merchants and customers guilty of desecrating the temple. Items being bought and sold included animals for sacrifice (John 2:14). Also present were those who exchanged one currency for another. This was needed because Roman coins and other forms of currency were deemed unacceptable for temple offerings. The temple was the place where God met with His people. This marketplace would have been obstructing worship, and specifically taking up space that had been set aside for Gentiles to worship. Evidently, both merchants and money changers were charging such excessive rates that the temple marketplace took on the atmosphere of a thieves' den (Matthew 21:13).
Obviously, selling books, having a raffle, doing fundraising, etc., is different from what was going on in the temple. Jesus was not necessarily angry that they were selling in the temple, but rather that selling was becoming the focus instead of God. Jesus was also angry that the moneychangers were taking advantage of people, many of whom were poor, who needed their services. Pigeons and other animals were required for the offering, and tithes in acceptable currency were also a requirement.
Such is not the case in today's churches. Purchases in a church bookstore or at a church craft sale, for example, are entirely voluntary. No purchase is necessary to attend worship. If a church does decide to sell something inside the church or to host a fundraiser, it should make sure that the selling does not receive undue attention and does not draw away from worship and the teaching of God's Word. Selling should also never be made "high-pressure."