Why does God wait?

Walking to work this morning, I came across a sign outside the local church that said:

What does God want?

But for some reason (probably short-sightedness), I read it as

Why does God wait?

And suddenly, I started wondering.

As a Seventh-day Adventist Christian, I believe that Jesus (God) will one day return to Earth to renew it. Pain and suffering will disappear, and we will live with Jesus for all of eternity in what is essentially heaven.

However, the reason why that hasn't happened yet is because God is waiting for the good news of his salvation - that Jesus has died for our sins and all we have to do is accept Jesus as our Saviour in order to obtain eternal life - to be shared with all the world.

I believe that.

I also believe that as Christians, we have a responsibility to share this great news with everybody.

But I still wonder, why does God wait?

It's easy to say that he's waiting so that everybody will have a chance to hear of the good news.

And yet, for every day that he waits, a few million more babies are born, most of who probably have no opportunity to hear about the good news.

In waiting, we may eventually end up with even more people who need to hear the news than those who have actually heard it.

So why does God wait?