There are, of course, different opinions on this issue. Some people feel that prayer must involve actively and explicitly making one’s thoughts known to God. Prayer should involve praising God, asking forgiveness for sins, and petitioning God for various things that we think are important.
But this is not necessarily the only way to pray. Christians believe that God is all-knowing and that God wants to be a part of our lives. Meditation is consistent with these ideas. When Christians meditate, they can simply open themselves up, without words, to the presence of God. As they invite God into their hearts, they are, in essence, praying. They are inviting God to share their very being, thus opening to him all the thoughts and intentions that they might otherwise express in prayer.
Thus, while some Christians think meditation is not prayer, others maintain that it is a form of prayer and is therefore appropriate.