When you come to Jesus Christ, you receive Christ into your heart. Jesus does not physically enter into your chest cavity and live there, but the Spirit of God comes and joins with the spirit of the believer. This is what is meant by the term "the indwelling Spirit." His function is to reproduce the life of Jesus in the believer. He will manifest the fruit of the Spirit in the believer's life. The nine attributes of Jesus that develop in the life of someone who has been born again and who has been indwelt by the Holy Spirit are love, joy, peace, longsuffering, kindness, goodness, faithfulness, gentleness, and self-control (Galatians 5:22-23).
In Romans 8:14, the apostle Paul tells us that those who are led by the Spirit are sons of God. We could transpose those words and say that the sons and daughters of God can expect the leading of the blessed Holy Spirit.
You might ask then, where does the constant struggle in the life of some Christians come from? Many Christians run into problems when they do not cooperate with the Spirit. We have a choice. The Spirit does not force Himself on us. For example, in the first century the apostles and elders in Jerusalem were debating a matter of doctrine. After they heard much discussion, they responded to the believers in Antioch, saying, "It seemed good to the Holy Spirit, and to us, to lay upon you no greater burden than these necessary things" (Acts 15:28). That was an awesome statement for those men to make. They were saying, in effect, that their opinion was equal to the opinion of the Holy Spirit. They said, "It seemed good to the Holy Spirit, and to us." You might ask yourself, if it seemed good to the Holy Spirit, who cares what the apostles thought about it? They were acknowledging a God-given partnership. They could choose whether or not to cooperate with the Holy Spirit. They can hold back and fail to acknowledge Him, or they can accept His leading to do what He wants them to do. They have that freedom, but they eventually have to deal with the blessings or problems resulting from their free decisions.
John the Baptist can be our role model. He said, "He must increase, but I must decrease" (John 3:30). Our wills and our egocentric natures have to decrease, whereas the Spirit of Jesus within us has to increase. This is a continuing process. Little by little, Christ is being made bigger, and we are being made smaller. If you fight that process and say, "I am going to assert myself and have my own way, but I will go to church on Sunday, acknowledge Christ, and take His benefits," you are going to be a defeated, immature Christian. The struggle will go on as long as you give your flesh, the world, and the devil a place in your life.