What does "kill the soul" mean in Matthew 10:28?

Is it so that “Immortality in God’s Word has no reference to the soul”? If this be so will you kindly explain Matthew 10:28 “Fear not them which kill the body, but are not able to kill the soul”

Immortality is immunity from death. Clearly man did not then possess immortality in that sense, when created, for he was warned he would die, if he ate the forbidden fruit. But what is death then? It certainly is not “annihilation” or a cessation of existence, for Adam and Eve Continued to exist after the fall. In fact no external change apparently took place in them. But a marked spiritual change occurred, for “They heard the voice of the Lord God walking in the garden. . . and Adam and his wife hid themselves from the presence of the Lord God” (Genesis 3:8). Death therefore is not cessation of existence, but separation of existence, that is existence out of harmony with God.

This spiritual death has been the condition of the whole human race ever since. When a man believes the gospel “he passes from death unto life” (John 5:24). He now possesses eternal life and has the assurance from God that “he will never perish” (John 10:28). This is immortaiity in the spiritual sense, “Verily, verily I say unto you, If a man keep my saying he shall never see death” (John 8:51). But the fall did not kill the body. To assure this, man was shut off from the tree of life and flow “it is appointed unto men once to die” (Hebrews 9:27). Even the body of the Christian “is dead, because of sin” (Romans 8:10). If he dies, his corruptible body will put OR incorruptibility at the Lord’s return, if he survives till then his mortal body will put on immortality. He has the immortality of the spiritual side of his being already included in the gift of eternal life, for that immortality is not only a bodily attribute is clear from the Words, “God Who only bath immortality” (1 Timothy 6:16) —that is in Flimseff, though, of course, He does communicate it. The special verse referred to, Matthew 10:28, merely states that the soul survives the body. Man may kill the latter, but cannot kill the former. This would be equally true of an Unconverted man, who will never cease to exist away from God, as of a converted man who will never cease to live with God.