Dear friend, prayer for Christians is an expression of a living relationship and spiritual fellowship with God. It is not an obligatory requirement to please God. So it is not fardh [an obligatory act] that man has to complete. Prayer is a manifestation of a living relationship with God. It is an outcome of a love relationship with God.

So prayer is a fruit of love not fear or obligation. Prayer is a fruit of a meaningful relationship with God the creator. It is not directed from a slave to his master. It is words of a son to his loving father. It is from a heart longing to be in fellowship with God. Christians believe that God is their Father. They do not mean by this a literal physical sense. The Bible explains it as "All who received him, to those who believed in his name, he gave the right to become children of God—children born not of natural descent, nor of human decision or husband’s will, but born of God". So our relationship with God in prayer is based on that fact that he is a loving Father and we are his children who love him dearly and want to be close to him.

This fellowship, this prayer, is not only five time a day. Prayer is an expression or utterance of a relationship and not just an event that we perform every day. The Bible confirmed this: "Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving, present your request to God." The Disciples of Christ also did the same: "They all joined together constantly [regularly] in prayer."

But prayer is an outcome of a continuous relationship with God all day, all week, all year, all of our life. We do not need to wash only from the outside to prepare for prayer, but we need especially to be washed from inside. We need a clean heart. This means clean from sin. In the book for Psalms [Al-Zabour], the prophet David prayed: "Create in me a clean heart, O God, and renew a steadfast spirit within me."

When Christians pray they do not repeat the same prayers or verses. They may be engaged in a conversation with God or even sit quietly in a moment of silence. We may stand or bow or kneel. Here is a prayer by the prophet David:

To you, O LORD, I lift up my soul; in you I trust, O my God. Show me your ways, O LORD, teach me your paths; guide me in your truth and teach me, for you are God my Savior, and my hope is in you all day long. Remember, O LORD, your great mercy and love, for they are from of old. Remember not the sins of my youth and my rebellious ways; according to your love remember me, for you are good, O LORD. Good and upright is the LORD; therefore he instructs sinners in his ways. He guides the humble in what is right and teaches them his way. All the ways of the LORD are loving and faithful for those who keep the demands of his covenant. For the sake of your name, O LORD, forgive my iniquity, though it is great….Turn to me and be gracious to me, for I am lonely and afflicted. The troubles of my heart have multiplied; free me from my anguish. Look upon my affliction and my distress and take away all my sins.

In Jesus’ time, people used prayers to show off how good they were. They wanted to show off their good deeds to other people. They were boasting that they were religious. That is why Jesus said the following: "And when you pray, do not be like the hypocrites, for they love to pray standing in the synagogues and on the street corners to be seen by men. I tell you the truth; they have received their reward in full. But when you pray, go into your room, close the door and pray to your Father, who is unseen. Then your father who sees what is done in secret, will reward you."

Another dimension in prayer is that Christians pray for each other. They pray for those who are ill and those who are going through difficult times. Praying for each other is an important bond between Christians.

It is stated in the Bible: "Is any one of you in trouble? He should pray. Is anyone happy? Let him sing songs of praise. Is anyone of you sick? Pray over him and anoint him with oil in the name of the Lord. And the prayer offered in faith will make the sick person well; the Lord will raise him up….Therefore confess your sins to each other and pray for each other so that you may be healed. The prayer of a righteous man is powerful and effective."

You have mentioned in your question that prayer is one of the five pillars of Islam. Every Muslim has the obligation to pray five times a day. Neglect of prayer would lead to the Muslim’s going to hell. One very significant aspect is that in Christianity prayer is not part of a system of good deeds. Christians believe that they are not saved by how much they pray each day. Not all the prayers in the world will be enough to pay or abolish the sins. The Bible stated this very clearly: "There is no difference, for all have sinned and fall short of the glory of God."

Only God through his mercy and grace can help us.