A popular evangelistic fad at the moment is to piggy-back on the current research into happiness. Since everyone is obsessed with being happy the general idea is that we show them how faith in Christ actually promotes happiness.
1. I like the idea of a soft apologetic, starting with a desire for personal happiness in popular culture and gently trying to turn that towards God. It is absolutely essential that Christians engage with contemporary social attitudes and research.
2. However, I've got questions about the fundamental premise of this approach. Usually it begins with a definition of happiness, with attempts to 'correct' society's defintion. Nevertheless the basic assumption is that the goal of humanity is to be happy and that Christianity is an aid to that goal.
I'm not sure about that. In the Sermon on the Mount Jesus said that the blessed are those who mourn. Paul talks about godly sorrow that leads to repentance in 2 Cor. 7. In other words sometimes being sad is a good thing, indeed sometimes what God wants for us.
Therefore I assume that you'd need to end up by challenging the overall assumption that God wants us to be happy
all the time. (NB I'm
NOT saying that God wants us to be sad all the time!) Hence instead of pointing everyone to Christ this strategy might, however unintentionally, encourage some to pursue happiness as their goal in life. Instead the gospel teaches us that true contentment and satisfaction in life is found when we pursue Christ as our goal in life.