Committing sins is a very serious matter. It is much more serious than people are often led to believe. A disciple of Jesus is someone who has repented of their sins. In Christ, they are set free from sin. They are no longer slaves of sin and no longer continue sinning otherwise they have not repented of their sins and they are deluding themselves.
Repentance
The noun which is commonly translated as "repentance" in the Bible is metanoia and literally means a change of mindset. The verb form, to repent, is metanoeo. The root word in question is the verb noeo and refers to the activity of the mind. The noun form of noeo is nous which is commonly translated as "mind."
Sin
If your hand or your foot causes you to stumble, cut it off and throw it from
you; it is better for you to enter life crippled or lame, than to have two hands
or two feet and be cast into the eternal fire.
Matthew 18:8
Jesus answered them, "Truly, truly, I say to you, everyone who commits sin is a slave of sin."
John 8:34.
Do you not know that when you present yourselves to someone as slaves for obedience, you are slaves of the one whom you obey, either of sin resulting in death, or of obedience resulting in righteousness?... when you were slaves of the sin, you were free from righteousness. What fruit, therefore, were you having then, in the things of which you are now ashamed? For the end of those things is death.
Romans 6
Do you not know that the unrighteous will not inherit the kingdom of God?
1 Corinthians 6:9
Awake to righteousness and do not sin for some have no knowledge of God. I speak this to your shame.
1 Corinthians 15:34.
No immoral or impure person or covetous man, who is an idolater, has an inheritance in the kingdom of Christ and God. Let no one deceive you with empty words, for because of these things the wrath of God comes upon the sons of disobedience.
Ephesians 5:5-6
Admonish those who sin in the presence of all, so that the rest may have fear [of sinning].
1 Timothy 5:20
Keep yourself free from sin.
1 Timothy 5:22
Pursue peace with all men, and holiness without which no one will see the Lord.
Hebrews 12:14
As obedient children, do not be conformed to the former lusts which were yours in your ignorance, but like the Holy One who called you, be holy yourselves also in all your conduct because it is written, "You shall be holy for I am holy." If you call upon as Father the One who impartially judges according to each one's work, conduct yourselves in fear during the time of your sojourn.
1 Peter 1:14-17
If we say that we have fellowship with Him and yet walk in the darkness, we lie and do not practice the truth.
1 John 1:6
By this we know that we have come to know him, if we keep his commands. He who says, "I have come to know him," and does not keep his commands, is a liar, and the truth is not in him; but whoever keeps his word, in him the love of God has truly been perfected. By this we know that we are in him: the one who says he abides in him ought himself to walk just as he walked.
1 John 2:3-6.
No one who abides in him sins; no one who sins has seen him or knows him.
1 John 3:6
Do not love the world nor the things in the world. If anyone loves the world, the love of the Father is not in him.
1 John 2:15.
By this the children of God and the children of the devil are obvious: anyone who does not do righteousness is not of God.
1 John 3:10.
He who commits sin is of the devil.
1 John 3:8
