At least I'm sure it wouldn't be a good life for me. Knowing Christ and the blessing He is in my life, I know that I would never be able to function without Him, let alone consider my life to be good. Maybe ignorance is bliss, but I don't think it is. Many who don't know the Lord personally complain of an emptiness that cannot be filled by the things of this world. They search, yet find no answer.
This is where our responsibility lies as Christians. We have found what ultimately satisfies, and now we need to do our best to share it with the world. A non-Christian can believe they are living a good life without knowing how much better it could potentially be. What an amazing and scary thing.