Yet not entirely with the fornicators of this world, or with the covetous, or extortioners, or with idolaters; for then must you needs go out of the world.
All Commentaries on 1 Corinthians 5:10 Go To 1 Corinthians 5
Ambrosiaster
AD 400
Paul means that it would be better to die than to mix with fellow believers who sin like the fornicator in question, because death would put an end to it sooner rather than later. Commentary on Paul’s Epistles.