Jesus was saying in Matthew 6:7 that we must not regard prayer as some kind of magical incantation, for that is how pagans pray. They recite certain phrases over and over again, with no understanding of what the words mean. In these contexts, prayers are used as mantras, with the hope that they will change the environment or the circumstances in which a person lives. New Age thinking is filled with this type of thing. Jesus did not commend such exercises as godly forms of prayer; rather, He linked the use of vain repetitions to paganism.
"And when you pray, do not use vain repetitions as the heathen do. For they think that they will be heard for their many words." (Matthew 6:7)
Christians can easily fall into a pattern of praying in a repetitious fashion, without engaging their minds. It bothers me sometimes when Christians gather for a meal and the host will say to someone there, "John, will you please say the grace for us?" The host doesn't ask for someone to lead in prayer but to say the grace. That kind of language suggests a mere recitation, not a prayer that comes from the heart.
We can even treat the Lord's Prayer this way. The Lord's Prayer is an integral part of the worship of multitudes of Christians. Worship services often include the recitation of the Lord's Prayer. The use of the Lord's Prayer has a rich history in the church, and whenever we pray it or hear it, we are reminded of those priorities that Jesus sets before us as objects for prayer. Don't get me wrong—I'm not opposed to the recitation of the Lord's Prayer. However, there is a danger that this use of the prayer may be nothing more than a recitation. The praying of the Lord's Prayer can become as mindless and as vain a repetition as the magical incantations and mantras that pagans use.
Jesus did not give the Lord's Prayer with the intention that it would be repeated mindlessly. When we pray the Lord's Prayer, we need to pray it thoughtfully, giving attention in our minds to its content. It is not a mantra to be repeated without the engagement of the mind or heart. It is an example of godly prayer.
Of course, repetition has great value. I've often said that one of my favorite liturgies in the life of the church is the traditional marriage ceremony. You've heard it many times: "Dearly beloved, we are gathered together here today in the presence of God and of these witnesses to unite this man and this woman in the holy bonds of marriage, which was instituted by God," and so it goes. It's a very brief service. It contains pledges, vows, charges, and prayers. For me, the more often I lead this liturgy or hear it, the more blessed I am by the content of it. That is, the more familiar I become with the language, the more I think about it and meditate on it, and I see afresh how rich it is in explaining to us the sanctity of marriage. So it is with the Lord's Prayer. Hearing it over and over again may lead us to mindless repetition, but it also may burn these words, and the underlying principles, into our minds. Repetition in and of itself is not a bad thing. In fact, it's one of the most important ingredients of learning, because it's the rare person who masters a concept or a principle by hearing it once.
This excerpt is taken from The Prayer of the Lord by R.C. Sproul.