Why should we preach the gospel? I know that some make the point that if God elects a person to salvation, it will happen regardless of whether I tell him today or wait until next week, or next year.
But it is better to learn sooner than later, and we see that even though God can decree our salvation ultimately, our free will can play a factor in the timing of our conversion.
We see this with Jonah and the great fish. In this story Jonah is told to preach to the Ninevites, but refuses God's decree. We know the story of the ship, the sailors, the curse, the expigation, the consumption, and the desperate prayer for deliverance. Jonah would preach as God decreed, but he undoubtedly been better off doing it sooner than later.
Or put another way, ought we to preach the gospel to a mother or father when their child is 3 years old and teachable, or several years later when the child is a rebellious teenagers swinging to the beat of the world?
How many ways can I state that sooner is better than later?