This is, of course, a matter on which people can differ. My own view is that there are a couple of different aspects to this.
First, there is definitely a personal aspect to living an effective and fruitful Christian life. In some ways, the most important thing for a Christian is their relationship with Jesus Christ. Since the center of what makes a person Christian is their faith in Jesus, Christians must engage in prayer on a regular basis. They must study the Bible to try to understand what God’s will is. It is impossible to be effective and fruitful as a Christian without doing this.
However, there is a second aspect to such a life and that is the way in which one bears witness through one’s own actions. Even though we cannot be saved by works, it is vital that Christians show their love of Jesus and of one another in their actions. If they can bear witness for God, both in words and in actions, they are more likely to be able to bring more people to God. This is extremely important in a time and a place where religious faith is dwindling to some degree.