What is the goal of the Christian life? Godliness born of obedience to Christ. Obedience unlocks the riches of the Christian experience. Prayer is what prompts and nurtures obedience, putting the heart into the proper "frame of mind" to desire obedience.
Of course, knowledge is also important because without it, we cannot know what God requires. However, knowledge and truth will remain abstract unless we commune with God in prayer. It is the Holy Spirit who teaches, inspires, and illumines God's Word to us. He mediates the Word of God and assists us in responding to the Father in prayer.
Prayer has a vital place in the life of the Christian. First, it is an absolute prerequisite for salvation. Some people cannot hear; yet though deaf, they can be saved. Some may not be able to see; yet though blind, they can be saved. Knowledge of the Good News--salvation through the atoning death and resurrection of Jesus Christ--will come from one source or another, but in the final analysis, a person must humbly ask God for salvation. The prayer of salvation is the one prayer of the wicked God has said he will hear.
What do those in heaven have in common? Several things. They have all been justified, having put their faith in the atonement of Christ. They are all praising God. And they have all prayed for salvation. To be without prayer is to be without God, Christ, the Holy Spirit, and the hope and reality of heaven.
Second, one of the surest marks of the Christian is his prayer life. One might pray and not be a Christian, but one could not possibly be a Christian and not pray. Romans 8:15 tells us that the spiritual adoption that has made us sons of God causes us to cry out in verbal expressions: "Abba! Father." Prayer is to the Christian what breath is to life, yet no duty of the Christian is so neglected.
Prayer, at least private prayer, is difficult to do out of a false motive. One might preach out of a false motive, as do the false prophets; one might be involved in Christian activities out of false motives. Many of the externals of religion might be done from false motives, but it is highly unlikely that anyone would commune with God out of some improper motive. Matthew 7 tells us that in the "last day," many will stand at the Judgment and tell Christ of their great and noble deeds done in his name, but his response will be that he does not know them.
So, we are invited, even commanded, to pray. Prayer is both a privilege and a duty, and any duty can become laborious. Prayer, like any means of growth for the Christian, requires work. In a sense, prayer is unnatural to us. Though we were created for fellowship and communion with God, the effects of the Fall have left most of us lazy and indifferent toward something as important as prayer. Rebirth quickens a new desire for communion with God, but sin resists the Spirit.
We can take comfort from the fact that God knows our hearts and hears our unspoken petitions more than the words that emanate from our lips. Whenever we are unable to express the deep feelings and emotions of our souls or when we are completely unclear about what it is for which we ought to be praying, the Holy Spirit intercedes for us. Romans 8:26-27 says, "the Spirit helps us in our weakness; for we do not know how to pray as we ought, but the Spirit himself intercedes for us with sighs too deep for words. And he who searches the hearts of men knows what is the mind of the Spirit, because the Spirit intercedes for the saints according to the will of God." When we don't know how to pray or what to pray for in a given situation, the Holy Spirit assists us. There is reason to believe from the text that if we pray incorrectly, the Holy Spirit corrects the error in our prayers before he takes them before the Father, for verse 27 tells us that he "intercedes for the saints according to the will of God."
Prayer is the secret of holiness--if holiness, indeed, has anything secretive about it. If we examine the lives of the great saints of the church, we find that they were great people of prayer. John Wesley once remarked that he didn't think much of ministers who didn't spend at least four hours per day in prayer. Luther said that he prayed regularly for an hour every day except when he experienced a particularly busy day. Then he prayed for two hours.
The neglect of prayer is a major cause of stagnation in the Christian life. Consider the example of Peter in Luke 22:39-62. Jesus went to the Mount of Olives to pray as was his custom and told his disciples, "Pray that you may not enter into temptation." The disciples fell asleep instead. The next thing Peter did was try to take on the Roman army with a sword; then he denied Christ. Peter did not pray and as a result fell into temptation. What is true of Peter is also true of all of us: we fall in private before we ever fall in public.
Is there a right and wrong time for prayer? Isaiah 50:4 talks about the morning as the time when God gives the desire to pray on a daily basis and about renewed confidence in God. But there are other passages that give times of prayer during all times of the day. No part of the day is set apart as being more sanctified than another. Jesus prayed in the morning, during the day, and sometimes all night long. There is evidence that he had a time set aside for prayer; however, considering the relationship Jesus had with the Father, we know that communion between them never stopped.
First Thessalonians 5:17 commands us to pray without ceasing. It means that we are to be in a continual state of communion with our Father.
Excerpt from Does Prayer Change Things? by R.C. Sproul