The basis of Christian joy is knowing JESUS. By faith we see him, walk with him, and commune with him. This joy is inexpressible and glorious because there is nothing which can harm you. You know everything will be alright no matter what happens. Anger, frustration, jealous, envy non of these can affect you emotionally because of the love of CHRIST which fills your inner being. A person which do not know JESUS can not fake this joy. This joy is a gift from GOD man can not fake this.