The Bible does not say the soul is mortal.For instance, the Bible says the ‘soul dies’. Ezekiel 18:4, et.al.
But it never says the soul is immortal.
People are taught that, but the Bible doesn’t say that.
King James Version
4 Behold, all souls are mine; as the soul of the father, so also the soul of the son is mine: the soul that sinneth, it shall die.
That verse means that the soul that sins will not have eternal life, which is a state of the soul that is near to God. That soul will continue to exist in the spiritual world, but it will be far from God.
That soul will be spiritually dead, but it will continue to EXIST in the spiritual realm after the body dies. A soul cannot die because it is not physical. Only physical things die.
When Jesus referred to eternal life, He was not referring to physical life of the body. He was referring a quality of life, spiritual life, loving God and being close to God.
The soul is eternal, the body perishes. That is why Jesus said: John 6:63 It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life
All the verses below refer to eternal life of the soul, not life of the physical body.
John 11:25-26 Jesus said to her, “I am the resurrection and the life. He who believes in Me, though he may die, he shall live. And whoever lives and believes in Me shall never die. Do you believe this?”
John 3:16 For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life.
1 John 5:13 I write these things to you who believe in the name of the Son of God that you may know that you have eternal life.
John 5:24 Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.
All souls will continue to exist in the spiritual world after the body dies but not all souls will have eternal life (everlasting life).
Eternal life refers to a “quality” of life, nearness to God which, according to Jesus, comes from believing in Him.
“The immortality of the spirit is mentioned in the Holy Books; it is the fundamental basis of the divine religions. Now punishments and rewards are said to be of two kinds: first, the rewards and punishments of this life; second, those of the other world. But the paradise and hell of existence are found in all the worlds of God, whether in this world or in the spiritual heavenly worlds. Gaining these rewards is the gaining of eternal life. That is why Christ said, “Act in such a way that you may find eternal life, and that you may be born of water and the spirit, so that you may enter into the Kingdom.” 2”
Some Answered Questions, p. 223
The souls of people who are distant from God will not have eternal life; although their soul will continue to exist in the spiritual world after their physical body dies they will be “as dead” compared to those souls who are close to God.
“In the same way, the souls who are veiled from God, although they exist in this world and in the world after death, are, in comparison with the holy existence of the children of the Kingdom of God, nonexisting and separated from God.”
Some Answered Questions, p. 243