Keeping all the Mitzvot of the Torah scrupulously and dedicating one's life to return others to the path of Torah and service of H'shem still would not be enough to earn him a place in Olam Habba without H'shem's infinite grace and generosity.
Although the world seems to run independently of H'shem, one must understand that its existence is being held up every single moment by the will of H'shem. It is for this reason, the Sages refer to H'shem as Makom, the place that the world stands on and is sustained by.
Gate Three, Chapter Two page 110
Leilu Nishmat Reb Jonathan Sacks a brilliant mind, a tremendous loss for Am Yisroel