REPENTANCE IS ESSENTIAL TO SALVATION
According to all of the various Greek lexicons, repentance means a change of mind that leads to a change of actions. When one repents in the New Testament, they cease from sinful acts and move forward by living the Christian life. These verses convey the meaning quite clearly. Before one can be accepted of God, they must repent of sin.
Mark 6:11-12
And whosoever shall not receive you, nor hear you, when ye depart thence, shake off the dust under your feet for a testimony against them. Verily I say unto you, It shall be more tolerable for Sodom and Gomorrha in the day of judgment, than for that city.
12And they went out, and preached that men should repent.Acts 2:38
Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
Acts 17:30
And the times of this ignorance God winked at; but now commandeth all men every where to repent:
2 Cor. 7:9-10
Now I rejoice, not that ye were made sorry, but that ye sorrowed to repentance: for ye were made sorry after a godly manner, that ye might receive damage by us in nothing.
10For godly sorrow worketh repentance to salvation not to be repented of: but the sorrow of the world worketh death.2 Peter 3:9
The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.
The verses shown all reflect the absolute necessity of repentance in the plan of salvation. In Acts 2, when asked, "what must we do (to receive salvation)" by those that heard him speak the gospel, Peter said frankly and forthrightly, "Repent".