Who is a Buddhist to say that they are happier than a Christian?
Or that he is the happiest man in the world?
As to true happiness…yes God is the only way to lasting…full happiness…
There are lots of “happiness” aspects in life… And lots of “hopes” in life along the way. From coffee ice-cream on a hot day…to various beloved persons in life. But happiness in not just an emotional thing…and these sometimes authentic moments of happiness (sometimes only apparent) are not full happiness…they are not full happiness.
"Day by day, man experiences many greater or lesser hopes, different in kind according to the different periods of his life. Sometimes one of these hopes may appear to be totally satisfying without any need for other hopes. Young people can have the hope of a great and fully satisfying love; the hope of a certain position in their profession, or of some success that will prove decisive for the rest of their lives. When these hopes are fulfilled, however, it becomes clear that they were not, in reality, the whole. It becomes evident that man has need of a hope that goes further. It becomes clear that only something infinite will suffice for him, something that will always be more than he can ever attain…
Let us say once again: we need the greater and lesser hopes that keep us going day by day. But these are not enough without the great hope, which must surpass everything else. This great hope can only be God, who encompasses the whole of reality and who can bestow upon us what we, by ourselves, cannot attain. The fact that it comes to us as a gift is actually part of hope. God is the foundation of hope: not any god, but the God who has a human face and who has loved us to the end, each one of us and humanity in its entirety. His Kingdom is not an imaginary hereafter, situated in a future that will never arrive; his Kingdom is present wherever he is loved and wherever his love reaches us. His love alone gives us the possibility of soberly persevering day by day, without ceasing to be spurred on by hope, in a world which by its very nature is imperfect. His love is at the same time our guarantee of the existence of what we only vaguely sense and which nevertheless, in our deepest self, we await: a life that is “truly” life." ~ Pope Benedict XVI Spe Salvi