The Chief Rabbi makes two points. The first is that each Jew has a responsibility to his ancestors to continue their heritage. Failing to do so is a serious neglect of duty. I know some people who find this powerful but I don't think that this is enough to motivate me to keep all of the laws of the Torah.It's certainly an interesting piece, and while I'd have to read it more carefully to form an opinion, I like Gil's point at the end which I think is the most important facet of kiruv, and truly, the continuity of Jewish life in general:
His second point is, to me, extremely powerful. Each Jew has an opportunity to be a part of something bigger, to transcend his own personal abilities and join a group spanning the world and the centuries, to not only follow in their footsteps but to add to their accomplishments -- to add a unique letter to their Torah scroll. Perhaps you can do that with other religions but as someone born Jewish, you have a unique opportunity to join the famous Jewish story and add your own chapter to it. If you have to ask why, then this argument is not for you. However, I believe that in this modern world of lonely disconnectedness, this is a powerful and attractive argument.
Yes, it is an emotional (rather than intellectual) argument. It is particularly effective in that sense. Of course, to most (I hope) people, Judaism still needs to be intellectually justifiable and satisfying. I believe it is. Certainly coming from R. Sacks, a man of great intellect, the argument has significant force. It also has the advantage of avoiding what I believe are the irresolvable arguments over proof and disproof.
It will pique their interest and then it is the job of the Orthodox community to demonstrate the beauty of Orthodox life and the continuity it represents with the past and the future.