9 The Lord is not slow in keeping his promise, as some understand slowness. Instead he is patient with you, not wanting anyone to perish, but everyone to come to repentance.

The delay of the return of Christ is related to the preaching of the gospel of the kingdom to the whole world.
God wants everyone to hear the gospel and does not want anyone to be lost forever. This does not mean that all will be saved, those who reject the grace and salvation of God, will remain lost.