Charles Spurgeon Commentary 1 Peter 4:6

"For unto this end was the gospel preached even to the dead, that they might be judged indeed according to men in the flesh, but live according to God in the spirit." — 1 Peter 4:6 (ASV)

for this cause was the gospel preached also to them that are dead, that they might be judged according to men in the flesh, but live according to God in the spirit.

Men who heard the gospel, and believed it, are now dead; they have undergone the sentence of death like other men; but, still, they are living "according to God in the spirit."