“Peter replied, “Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit.” (Acts 2:38, NIV)
Are we seriously asking if repentance is optional? No, it is a rhetorical question, like Paul asking, “What shall we say then? Shall we go on sinning that grace may increase?” (Romans 6:1). Paul’s response, “By no means!” The answer also applies to our question. Intellectually and theologically, we understand for there to be a transformation in one’s life, there must be a change of mind and orientation. When the trajectory of one’s life is away from God, repentance requires a change of direction.
Not infrequently, we come across reports and surveys lamenting the spiritual condition of the church today. In many cases, there is no discernible difference between “professing Christians” and the world in areas of pornography and sexual purity, divorce, and other areas of morality and ethics. If there is no difference in these areas, then what is the point?
Without repentance, it is as though an effort is made to put the “garments of salvation” on over the “filthy rags of our own righteousness.” (Isaiah 64:6, Isaiah 61:10). If our best is “filthy rags,” then the image portrayed of “putting on the Lord Jesus Christ” (Romans 13:14) seems absurd. Paul further expands on the importance of taking off the old nature before putting on the new:
“Strip yourselves of your former nature [put off and discard your old unrenewed self] which characterized your previous manner of life and becomes corrupt through lusts and desires that spring from delusion; And be constantly renewed in the spirit of your mind [having a fresh mental and spiritual attitude], And put on the new nature (the regenerate self) created in God’s image, [Godlike] in true righteousness and holiness.” (Ephesians 4:22–24, AMP)
In our efforts to “get people saved,” we can sometimes preempt or short-circuit the work of the Holy Spirit. On the day of Pentecost, Peter, filled with the Holy Spirit, is preaching the church’s first message, but from the text, there is no indication that he is about to wrap things up or give an invitation. Under the conviction of the Holy Spirit, the crowd interrupted him and asked, “what must we do to be saved?”
We are not saying that there is no place for invitations or altar calls, but it is the Holy Spirit who makes hearts ready. Ready not only to receive new life in Christ, but ready to repent and renounce the world, the flesh, and the devil. In the early days of the church, repentance and renunciation were not implied or assumed, they were done deliberately at the time of baptism.
In making a public profession of faith, the members of the Early Church would stand, face west and say, “I renounce you, Satan, and all your works and all your ways.” …More specifically, the Early Church members would renounce every counterfeit religious experience they had ever had, every false vow or pledge they had made, and every false teacher or doctrine in which they had believed. They would then face east and make a public declaration to follow Christ and believe the truth.
Another practice of the early church was to baptize people naked. This reinforces the idea of removing our old garments and casting them aside, symbolizing the renunciation of our old lives in preparation for receiving a new life in Christ.
St Cyril of Jerusalem referred to the newly baptized as ‘undergoing a corporeal transformation: stripped naked … you were imitating Christ naked upon the cross …It was also common practice for the naked baptismal candidates to be clothed in white garments following their immersion in water, to signify their transfigured and purified state… 
We are not ready to advocate naked baptisms even though there are strong allusions about turning from our old ways of life, a renunciation of former “secret and shameful ways,” (2 Corinthians 4:2) and then: “Put on your new nature, and be renewed as you learn to know your Creator and become like him.” (Colossians 3:10, NLT).
Repentance is not optional! According to Hebrews 6:1, repentance is elementary teaching that is foundational to our new life in Christ. If an attempt is made to begin a new life in Christ without repentance, it will be like trying to put on brand-new clothes without first removing the old smelly, dirty ones. It might work for a while, but eventually, everyone will know that something is not quite right. Delayed or deferred repentance will hamper or stunt spiritual growth.
As we are convinced that repentance is vital and foundational, any attempt to defer will impede spiritual progress. The wise builder (Luke 6:46-49), by repenting, dug down deep to reach the foundation rock so that when he built his house, it would last no matter what storms would come against it. Repentance is how we remove the debris and rubble, that is the sin in our lives so that we can build our lives on the “Solid Rock!”
“Repent, then, and turn to God, so that your sins may be wiped out, that times of refreshing may come from the Lord…” (Acts 3:19, NIV)
 David Torevell, Losing the Sacred: Ritual, Modernity, and Liturgical Reform (London; New York: T&T Clark, 2004), 49–50.