He called them together with the workers of similar occupation, and said: "Men, you know that we have our prosperity by this trade. Moreover you see and hear that not only at Ephesus, but throughout almost all Asia, this Paul has persuaded and turned away many people, saying that they are not gods which are made with hands. So not only is this trade of ours in danger of falling into disrepute, but also the temple of the great goddess Diana may be despised and her magnificence destroyed, whom all Asia and the world worship." Acts 19:25-27
Not only was Demetrius the silversmith upset that his income from making idols would be interrupted by people turning to Christ, he was jealous for the “great goddess Diana” and the magnificence of her temple. From this we have a window into another reason people are zealous for false religion. Besides the money, their reputation was at stake. The temple of Diana was indeed magnificent. It would have been considered a wonder of the world in that day. And, “We are all so devoted to it,” Demetrius must have reasoned, “What would we do if this were to pass away?!”
There are people who oppose Christ and the gospel because they have invested themselves so heavily in false religion that, in order to follow Christ, they cannot bring themselves to acknowledge that their religion is wrong. They have “done so much” they cannot bring themselves to admit that it was emptiness and all for naught. Pride disallows them to change, which is why they must be born again. It is only when one is given a new heart and affections that one can forsake falsehood to follow the One who is the Truth.
I know people who are imprisoned in false religion who do not even know much about their religion. They are devoted to being “members of that team” more than they are to teachings of their religion. “Once a Dodger fan, always a Dodger fan.” You may have been a team member of another religion (or perversion of Christianity), but God showered you with His grace. Pray that He will do the same to those who are blinded by their jealousy for their own “temples of Diana.”