The basis for our joy is that we know our souls have been saved by the forgiveness given in Christ. When the disciples went out to preach and work healings and deliverences and then came back they were estatic. But the Lord said that was nice that they rejoiced for that yet he said rejoice instead that your names are
written in the book of life.
Joy is connected with emotions in the sence that joy can be expressed by a show of gladness and happiness.
The world looks for outside things to bring them their sense of joy. Like the illusion of security, having a lot of money or having a lot of possessions, among other things. It really doesn't come from within by the Holy Spirit like it does for us
Joy is genuine in a beliver when a sense of gladness is still apparent even when a person is going through a time of hard trials, suffering or persecution.