1 Corinthians 15:12-14 — Now if Christ be preached that he rose from the dead, how say some among you that there is no resurrection of the dead? But if there be no resurrection of the dead, then is Christ not risen: and if Christ be not risen, then is our preaching vain, and your faith is also vain.

It seems I’m on a “back-to-basics” journey at the moment — but maybe this piece is the punchline. I’ve talked about sin, and about Holy God, but there’s a truth that adds force to the discussion. We all have an eternal future.
There’s nothing new about skepticism about the idea of life after death. Despite Old Testament scriptural support for resurrection, a major Jewish sect — the Sadducees — rejected it. More significantly for the letter to Corinth, the Greeks and Romans living there had no background of a belief in eternity.
Nowadays, it’s not surprising that non-Christians don’t believe in any kind of life after death. What is surprising is that there are Christians who don’t believe in the idea either. You might ask if it really matters, so long as they have Jesus as their Lord? It does.
If there is no afterlife then, as Paul points out, Jesus’s sacrifice for us is of no value — whatever our fate would be before we accepted Him as Lord would be unchanged by His death. In fact, all we believe would be mistaken.
If there is no afterlife, the world’s pursuit of “all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life” might seem perfectly reasonable!
However there is an afterlife… we do have an eternal future. J. C. Ryle, the first Anglican Bishop of the English city of Liverpool laid out the alternatives that await us:

Let us settle it then in our minds, for one thing, that the future happiness of those who are saved is eternal. However little we may understand it, it is something that will have no end: it will never cease, never grow old, never decay, and never die. “God will fill us with joy in His presence, with eternal pleasures at His right hand.” (Psalm 16:11) … For another thing, let us settle it in our minds, that the future misery of the unbelievers who are lost is eternal. I am aware that this is an awful truth, and flesh and blood naturally shrink from the contemplation of it.

There is an afterlife. It follows that sin, the offending of a Holy God, has terrible eternal consequences!