Does Paul's teaching require Christians to give a set amount?
No. Under Paul’s teaching, believers are under no mandate to give a set amount or fixed percentage. Giving is left to the believer’s free will, according to how God has prospered them. Ten percent may serve as a guideline, but it is not enforced, and failure to give it does not bring divine punishment.
Les explains that Paul’s instruction to the Corinthians was not to lay by in store as a tithe but as God had prospered them. That, he says, is the beauty of the Christian life and God’s grace: God has left believers with free will. They can give as much as they want, and God is not putting the thumb on their head demanding 10 percent. Ten percent is a guideline for a giver, but God is not going to zap someone who does not give it. A believer may lose some reward in glory, yet there is no mandate under Paul’s teaching to give a set amount. Giving is up to the believer, according to how God has prospered him. Paul also wanted the collection done before he arrived so it would not be given under his influence, as if people were digging into another pocket to impress him.