In the Gospel of Mark we often read about Jesus telling the people to repent:
After John was put in prison, Jesus went into Galilee, proclaiming the good news of God. "The time has come," he said. "The kingdom of God is near. Repent and believe the good news!" (Mark 1:14-15)
While Jesus was having dinner at Levi's house, many tax collectors and "sinners" were eating with him and his disciples, for there were many who followed him. When the teachers of the law who were Pharisees saw him eating with the "sinners" and tax collectors, they asked his disciples: "Why does he eat with tax collectors and 'sinners'?" On hearing this, Jesus said to them, "It is not the healthy who need a doctor, but the sick. I have not come to call the righteous, but sinners." (Mark 2:15-17)
His disciples also preached the same:
Then Jesus went around teaching from village to village. Calling the Twelve to him, he sent them out two by two and gave them authority over evil[a] spirits. These were his instructions: "Take nothing for the journey except a staff?no bread, no bag, no money in your belts. Wear sandals but not an extra tunic. Whenever you enter a house, stay there until you leave that town. And if any place will not welcome you or listen to you, shake the dust off your feet when you leave, as a testimony against them." They went out and preached that people should repent. (Mark 6:7-12)
So both Jesus and the disciples were telling the people to repent. Now the question I ask is this, repent to what? This was before Jesus supposedly sacrificed himself for the sins of the world, and the context of these verses don't indicate or show that Jesus was telling the people to repent by believing in his future death and resurrection, hence we need to ask what are the people supposed to repent to? Now for a believer like me, I know what repentance is, and I don't ask the question because I'm confused about the matter. I ask the question because theologically what Jesus is teaching doesn't fit in with the Christian doctrine of Jesus' sacrifice on the cross.
Think of it, the door of repentance and saving is open for the people, and this is before Jesus is sacrificed for the sins of the world, this is the sacrifice of all sacrifices, the one that will finally save the people. Yet if the people could already repent and be saved BEFORE this event took place, then it shows that this event wasn't needed at all because there was already a means of being saved! The people are being told to repent, but obviously not to repent to Jesus' sacrifice because it hasn't happened yet, and neither is he mentioning it, so again, there was already a system in place that allowed people to be saved, and this was by repentance, and repentance is repentance, it is returning back to God by obeying him and abandoning your sins!
Christian commentator Adam Clarke has this to say concerning Mark 1:
Here are four points worthy of deep attention, in the preaching of the Son of God.
1. Every thing that is done is according to a plan laid by the Divine wisdom, and never performed till the time appointed was filled up.
2. That the kingdom and reign of sin are to be destroyed, and the kingdom of grace and heaven established in their place.
3. That the kingdom of God, and his reign by grace, begins with repentance for past sins.
4. That this reign of grace is at hand; and that nothing but an obstinate perseverance in sin and impenitence can keep any soul out of it; and that now is the accepted time to enter in. (http://studylight.org/com/acc/view.cgi?book=mr&chapter=001)
So people could repent for their past sins? If that was the case, then why did Jesus need to sacrifice himself for the sins of the world if people could already repent for their past sins?! Again, the obvious answer is that the sacrifice of the cross was not needed, as there was already a system in place that allowed people to repent and be saved.
So much for the ultimate sacrifice!
And Allah Knows Best!