The verse above was spoken during a time of suffering and persecution. They can rejoice in suffering and persecution because hope is a driving force within us. When persons lose their hope they lose not only their future but also their present. Conversely, when we gain hope we gain not only a future but also a present. Hope is a driving force within people's lives.
Some people hope for wealth and fame.
Some people hope for business or job success. When we hope for good and glorious times through Christ we are confident and assured these times will become our reality. Because we have a hope for glorious times we can spend with God in heaven, we can rejoice.