In writing a “Kantian” defense of Catholic sexual teaching some time ago, I accepted the artificial restraint of not mentioning God. This effectively takes a partial view of Catholic moral teaching. It is as if a general practitioner only looked at your skeleton during an annual check-up, indifferent to your beating heart. I began by mentioning several ways to fend off the inevitable; let us finally face the inevitable.
Christians do not hope for the end of Creation; we expect it and should be prepared.
If the death of the universe were to come, there would still be no problem with the Church’s teaching, though the answer comes from an unexpected quarter: God has a plan, and we live this out by discerning our particular vocation. This is no cop-out. Vocations are part of complete Catholic teaching, as inseparable as the Mass. We cannot single out “what if we all behaved like Catholics sexually” to impugn the Church because “behaving like Catholics sexually” does not mean we behave like Catholics in other matters.
With this in mind, suppose we Catholics found our resources completely exhausted; that we really did have nowhere else to turn; that billions and billions years from now the universe finally dies, slowly, coldly of heat death — we may find that our vocations may have prayerfully become some flavor of religious or secular continence. But suppose that God does not call us to continence, for not even continence will prevent the end of things. If our universal vocation becomes at this point not just holiness but holiness in what we call matrimony, perhaps the best use of the last bit of energy in the universe would be conceiving the last new life our Cosmos ever produced.
Just imagine: One lonely spermatozoon racing from the final stillness which would bring Creation to a final winter, this cell only just ahead of the collapsing cosmos. Finally, then at once, it meets its final end — and, in another sense, we meet ours — in the last mother’s last ovum. In bold defiance of the lord of this world, in bold obedience to the Lord of All, the last act of life is new life. One last act emulating the cross: From death, life; by the will of God.
Prodigal No More 