1. Most large churches I know of have bookstands from which one can buy religious books any day of the week, including Sunday. They may call it "donation" on the bookrack, but we know what's being said.
2. Gentile Christian's Freedom from the old legal code of the Old Testament is something that most Christians fail to act on, even though many of them mouth things that show they know that they are dead to the law by the body of Christ. The Sabbath was NOT one of the Old Testament rules that the Acts 15 Jerusalem Council required the Gentile Christians to observe. Those four were:
Acts 15 28 It seemed good to the Holy Spirit and to us not to burden you with anything beyond the following requirements: 29 You are to abstain from food sacrificed to idols, from blood, from the meat of strangled animals and from sexual immorality. You will do well to avoid these things. Farewell. 30 The men were sent off and went down to Antioch, where they gathered the church together and delivered the letter.
3. Paul emphasizes the above for Gentile Christians in his letter to the Colossians:
Colossians 2
15 And having disarmed the powers and authorities, he made a public spectacle of them, triumphing over them by the cross. 16 Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day. 17 These are a shadow of the things that were to come; the reality, however, is found in Christ.