Matthew 18:8 “If your hand or foot causes you to sin, cut it off and cast it from you. It is better for you to enter into life lame or maimed, rather than having two hands or two feet, to be cast into the everlasting fire.”
Jesus did not equivocate on our fallen nature which is to sin. He was quite aware of the temporary fleeting joy we have to sin based on that fallen depraved nature of ours and provided a stern warning.
In the command to cut your hand or foot off or in another place He says “gouge out your eyes if it causes you to sin”, He was exhorting how dead set serious we must be about repentance and the fight our temptations to sin. But much more so how gravely the situation is without He as your Savior.
Those who thought they could be saved by being sinless, Jesus said there would come a time when you would literally need to maim yourself in order not to sin. Because that is our fallen nature, an innate desire where the joy is temporary but we continue to seek it.
And this desire just doesn’t all together go away upon being born-again, but at that point we realize there is a war going on in our members. In Romans 7, the Apostle Paul describes this in detail. Our hearts and minds desire holiness, and our sinful flesh continues to go after that temporary joy of sin. Paul gives the solution at the end of Romans 7.
21 I find then a law, that evil is present with me, the one who wills to do good. 22 For I delight in the law of God according to the inward man. 23 But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members. 24 O wretched man that I am! Who will deliver me from this body of death? 25 I thank God—through Jesus Christ our Lord! So then, with the mind I myself serve the law of God, but with the flesh the law of sin.
Paul was saying that this war between the flesh and our spirit will continue on until God takes us home.
Now if we go back to what Jesus said, He contrasts the temporary joy of sin to an eternal torment. He says “well if you want that temporary sinful joy to rule you, you will have eternal hell to look forward to where there will be no more joy”. So the command is to continue to REPENT! And those who have been born-again/saved are now capable TO repent! Those who have not, well like He said you would need to literally destroy your physical fallen body from the beginning in order to be saved outside of Him.
Since there is a war between the flesh and spirit, we must turn to the Holy Spirit to win the daily battles. And don’t be fooled, as a Christian there is this daily battle going on and I said, you only realize there is a battle once you have been saved/born-again. Unlike unbelievers, you have a deadly weapon in your arsenal, who is the Holy Spirit. So call upon Him! When Jesus said in the Lord’s prayer “and lead us NOT into temptation”, He was indicating that type of dependence we are to have on Him.