Religion addresses the deep spiritual needs in the human subconscious. As the most successful religion in history, Christianity seems to be doing a good job while Buddhism is dying out in its native India.
I don’t see Siddhartha to be wiser than Christ . Buddha knew neither more nor less about life and death than Christ. In fact, they both knew zeros as Confucius said it honestly and humbly: 不知生,焉知死.