Unless there will never again be new light, they aren't quite the truth, are they?
I wouldn't drink a glass of water that I knew contained only one drop of poison in it. It might be 99.9% pure, but still have that poison and kill you. Likewise, why would I put my trust in a belief system that is still in beta testing?
If you think JWs are the closest to the truth, how do you know? Especially if you are born into the organization. Have you actually studied all other religions to know that for a fact? Or is the knowledge you have about other religions only what the Society's publications have told you?
So what is the alternative if JWs don't have the truth? Become a genuine truth seeker and find what's right for you. Value empirical evidence over anecdotal.