Peter says NOTHING about going to hell for the backslider who is truly saved.
It defies logic to say that a backslider is truly saved. What's more, Peter said that there were things that we are to do to make our calling and election sure.
2 Peter 1
[3] According as his divine power hath given unto us all things that pertain unto life and godliness, through the knowledge of him that hath called us to glory and virtue:
[4] Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust.
[5] And beside this, giving all diligence, add to your faith virtue; and to virtue knowledge;
[6] And to knowledge temperance; and to temperance patience; and to patience godliness;
[7] And to godliness brotherly kindness; and to brotherly kindness charity.
[8] For if these things be in you, and abound, they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ.
[9] But he that lacketh these things is blind, and cannot see afar off, and hath forgotten that he was purged from his old sins.
[10]Wherefore the rather, brethren, give diligence
to make your calling and election sure: for if ye do these things, ye shall never fall:
[11] For so an entrance shall be ministered unto you abundantly into the everlasting kingdom of our Lord and Saviour Jesus Christ.
I quoted John 10:27-29 where Jesus said NO ONE is able to pluck a believer out of His Father's hand and His hand. That is called eternal security.
My sheep hear my voice, and I know them, and they follow me: 28 And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand. 29 My Father, which gave them me, is greater than all; and no man is able to pluck them out of my Father’s hand. Jn. 10:27–29.
In the Scripture that you cited, Jesus said that His sheep hear His voice and
follow Him. Backsliders are no longer following Jesus; they are serving their flesh, not Jesus. No man can serve two masters. We either serve Jesus or sin. When Jesus forgave the woman caught in adultery, this is what He said:
John 8
[10] When Jesus had lifted up himself, and saw none but the woman, he said unto her, Woman, where are those thine accusers? hath no man condemned thee?
[11] She said, No man, Lord. And Jesus said unto her, Neither do I condemn thee: go, and sin no more.
[12] Then spake Jesus again unto them, saying, I am the light of the world: he that followeth me shall not walk in
darkness, but shall have the light of life.
When Jesus spoke, He referred to darkness as being sin.
John 3
[17]For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
[18] He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
[19] And this is the condemnation, that light is come into the world, and men loved
darkness rather than light, because their deeds were evil.
[20] For every one that doeth evil hateth the light, neither cometh to the light, lest his deeds should be reproved.
1 John 1
[5] This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all.
[6]If we say that we have fellowship with him, and walk in
darkness, we lie, and do not the truth:
[7] But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.
So friend, as you can see, we cannot serve darkness and the Light too. It's one or the other. Backsliders are currently serving darkness again; they would need to confess and forsake their sins to be readmitted onto the narrow road of Salvation. Otherwise, they will die in their sins and go to hell. Tragic indeed. The cry is
"Please turn to Jesus while you still have time!".