Our verse today is Mark 6:12: "So they went out and proclaimed that people should repent." The disciples were sent out two by two by Jesus to villages all around them. Their primary message was that the kingdom of God had come to earth. As a result of receiving this message, the people were called to repentance. Note that repentance was not a suggestion. It was not strongly encouraged. The told people they "should" repent. It's a very important part of the Gospel message.
What is repentance? It's a change of heart and mind. It's moving in one direction and then deciding to move in the completely opposite direction. It's setting one's mind and heart to obey the will of the Father in heaven. It's dying to self and sin. It's being raised to Jesus and new life. Someone once said the best definition he'd ever heard of repentance is "Stop it." We stop doing that which is offensive to a holy God.
How does one repent? By hearing the Gospel of the kingdom of God through Jesus. It's by hearing the message of God's grace. When someone is touched by Jesus' forgiveness, repentance always occurs. In response to his grace, mercy and kindness on the cross, we repent. After having experienced his death for our sins, him taking our place on the cross, what else can we do? How can we keep on sinning knowing what he has done for us?
Does repentance occur before the cross? How can it? Why would someone repent of their sins before experiencing Jesus' profound forgiveness on the cross? Repentance must be in response to the marvelous message of God's kingdom having come to earth.
But make no mistake about it: repentance must occur if you've decided to follow Jesus. If you say you love Jesus but continue in your sins, you are lying. Yes, those of us who love Jesus do still sin. But we don't want to. It's not our hearts. It's not our minds. Our most fervent desire is to please the Father. We will not continue in our sins. The key word is "continue."
Repentance from our sins is not an option for those of us who know Jesus. That's why it was a key part of the disciples' message when they were sent out two by two.