Aside from considerations of eternity, are Christians as happy or happier than the people of this world?

Putting apart eternity after life a Christian following God's laws is happy even in this world because by doing so you feel peace inside yourself. Even if they are atheist they still feel what is good and what is bad to do. God's commandments are written first in oneself no what what his belief is. So if you observe this and do what you feel you are doing good you will be happy even now. The kingdom of God starts from this world with the peace that one has in his heart.