The single most important task that Jesus came to earth as a Man was to save us from our sins (Mt.1:21). This salvation includes forgiveness of all the sins we have committed and also our deliverance from our old habit of sinning so that we can be transformed in our nature to become like Jesus. After coming to faith in Jesus and receiving forgiveness, God's goal for us is that we should stop sinning (1Jn.2:1). If we are not moving towards this goal, there is even a chance that we have not really come to know God (1Co.15:34).
What is our approach towards sin after we have been born again? Is it all about receiving forgiveness of sins whenever we sin? In that case, it doesn't occur to us that God wants us to stop sinning! We imagine that God has accepted us and made us His children, and now we are safe because there is forgiveness for us. All we need to do is to confess our sins!
Certainly, God realises that after we are born again we are not going to become sinless and that we might fall into sin. So He has made the provision in His grace for our forgiveness (1Jn.1:9;2:1). But that doesn't mean that we can live like the rest of the world, seeking enjoyment and pleasure, trying to make a name for ourselves, etc. That path will invariably put less focus on stopping sinning. But God's plan for us is that we should stop sinning!
It doesn't mean that 'stopping to sin' will result in our becoming sinless. As long as we are on the earth, we will carry with us parts of our old nature (our flesh) with its sinful desires, and we are going to be tempted through these desires all the time (Ja.1:14,15). No one can assume that he will never fall. There is forgiveness if we fall, but the question is, is our heart bent on not sinning, and every time we are tempted in the different situations of life, are we going to fight against the temptation in order to avoid giving in to sin? Isn't there a big difference between these two ways of living?
The Bible talks much about 'overcomers'. Are these Christians who live more or less like the rest of the people but who bank on forgiveness to take them to be with God when they die? Obviously not! These overcomers are those who have been paying serious attention to overcoming every temptation they were faced with, whether it concerned their action, speech, thought, motives or intentions (He.4:12). These are the ones who add 'virtue to their faith', not just becoming content with their faith (2Pe.1:5).
Some people seem to think that always trying to 'overcome sin' will be a morbid, monotonous life without any fun. But actually, the more we learn to overcome, the happier we will be, the closer we can get to God, the more insight and wisdom we can have for our daily life, the more useful we can become to other people, and the better off we will be in eternity.
On the other hand, think of the regret we will have in eternity if we have wasted our salvation on earth (Mt.16:26)!