What's a good reason to party?
People try and do things that cause them to feel joy or pleasure. As Christians, what would cause you to throw a celebration? To dance? For me, the best day ever is when I get to witness someone putting on Christ in baptism, having their sins forgiven and receiving the gift of the Holy Spirit.
In Luke 15, the Jesus tells a story about a son who took his inheritance and left his family. He blew all his money and eventually returned, destitute. His father was overjoyed, and there was "music and dancing." The father who welcomed the son back said, "We had to celebrate and rejoice, for this brother of yours was dead and has begun to live, and was lost and has been found.’”
What causes God to celebrate should do the same for us, and like all things that are joyful, we should seek out such opportunities! Let's find more souls to redeem!