He said the fact that they loved and trusted Jesus should cause them to greatly rejoice. Christianity by design is to create that joy in any person who is converted to Christ, who makes a commitment to God. When a person chooses to turn from evil and to Christ, When a person in faith commits, When a person is truly converted to Christ, When a person expresses all this by being baptized into Christ, One of the natural expressions of relationship with God is joy. That joy exists for two basic reasons. The Christian is given a blessing and a purpose.
Christians are different.
If you associate with the Christian, you can sense the difference. The difference is real, it is genuine, because the Christian has a purpose that is bigger than life, and is even bigger than death. That purpose affects the way that the Christian does things. It affects the way that the Christians treats people. It affects every aspect of the Christian's life.