Death means separation. The first death is your soul’s separation from the body. This is physical death. Both righteous and wicked go through death.
The Second Death is your soul’s separation from God. It is written that the spirit goes back to God who gave it and we know that the spirit gives life, and that no one can live but for God’s spirit/breath. Only the wicked suffer the Second Death. There is a physical death and a spiritual one, just as there is a physical body and a spiritual one for those that belong to God and are granted eternal life.
Revelation 20:13-15
And the sea gave up the dead which were in it, and death and Hades gave up the dead which were in them; and they were judged, every one of them according to their deeds. Then death and Hades were thrown into the lake of fire. This is the second death, the lake of fire. And if anyone’s name was not found written in the book of life, he was thrown into the lake of fire.
Thus the Second Death is eternal and final. Once a person is subjected to the Second Death, they are separated from the source of all life, they are no longer living. It is clearly written that eternal life is only for the righteous.
John 3:16
For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
Eternal life is certainly not for the wicked. God is the God of the Living not the Dead. If a soul can live in Hell for eternity, then that is eternal life, but in the wrong location. Scripture clearly does not teach that the judged wicked will live forever regardless of their location. In the world to come, there will be no more death, pain, or crying. For the former things will have passed away.
God is great and merciful. He is full of grace. He is a God of love. His justice and severity is at its extreme when he destroys the wicked. He also disciplines his own children while in the world, but for good reason. Everything he does is for good. He is the God of all good, Jesus taught this clearly in Mark 10:18.
And Jesus said to him, “Why do you call me good? No one is good except God alone.
I have faith that God is good and right. And all the suffering now cannot be compared to the glory to come. We should all be thankful that the greatest power there is, is God who is love.
For more information on the death of the wicked, see ‘Is Hell eternal?‘.