"And these shall go away into everlasting punishment: but the righteous into life eternal." Matthew 25:46

It is well to notice that Jesus did not say that the wicked would suffer "everlasting punishing." He said "everlasting punishment." What is the punishment for sin? The punishment is destruction, and it is of eternal duration (see on 2 Thessalonians 1:9). In other words, it is a destruction which never ends, because there will be no resurrection from that destruction.

Paul says, "the wages of sin is death." Romans 6:23. John describes that death as "the second death" in Revelation 21:8. That death or destruction will be eternal.