As a logical Systems Analyst I will admit right up front that I do not understand logically how prayer works or how it can hold so much power. I do know, however, what scripture says and I believe scripture is true. There are 104 verses in the scriptures that talk about prayer.
Here are some of them in the New Testament:
Mat_17:21 ["But this kind does not go out except by prayer and fasting."]
Mat_21:13 And He said to them, "It is written, `MY HOUSE SHALL BE CALLED A HOUSE OF PRAYER'; but you are making it a ROBBERS' DEN."
Mat_21:22 "And all things you ask in prayer, believing, you will receive."
Mar_9:29 And He said to them, "This kind cannot come out by anything but prayer."
Mar_11:17 And He began to teach and say to them, "Is it not written, `MY HOUSE SHALL BE CALLED A HOUSE OF PRAYER FOR ALL THE NATIONS'? But you have made it a ROBBERS' DEN."
Luk_1:10 And the whole multitude of the people were in prayer outside at the hour of the incense offering.
Luk_6:12 It was at this time that He went off to the mountain to pray, and He spent the whole night in prayer to God.
Luk_19:46 saying to them, "It is written, `AND MY HOUSE SHALL BE A HOUSE OF PRAYER,' but you have made it a ROBBERS' DEN."
Luk_22:45 When He rose from prayer, He came to the disciples and found them sleeping from sorrow,
Act_1:14 These all with one mind were continually devoting themselves to prayer, along with the women, and Mary the mother of Jesus, and with His brothers.
Act_2:42 They were continually devoting themselves to the apostles' teaching and to fellowship, to the breaking of bread and to prayer.
Act_3:1 Now Peter and John were going up to the temple at the ninth hour, the hour of prayer.
Act_6:4 "But we will devote ourselves to prayer and to the ministry of the word."
Act_10:31 and he said, `Cornelius, your prayer has been heard and your alms have been remembered before God.
Act_12:5 So Peter was kept in the prison, but prayer for him was being made fervently by the church to God.
Act_16:13 And on the Sabbath day we went outside the gate to a riverside, where we were supposing that there would be a place of prayer; and we sat down and began speaking to the women who had assembled.
Act_16:16 It happened that as we were going to the place of prayer, a slave-girl having a spirit of divination met us, who was bringing her masters much profit by fortune-telling.
Rom_10:1 Brethren, my heart's desire and my prayer to God for them is for their salvation.
Rom_12:12 rejoicing in hope, persevering in tribulation, devoted to prayer,
1Co_7:5 Stop depriving one another, except by agreement for a time, so that you may devote yourselves to prayer, and come together again so that Satan will not tempt you because of your lack of self-control.
2Co_9:14 while they also, by prayer on your behalf, yearn for you because of the surpassing grace of God in you.
Eph_6:18 With all prayer and petition pray at all times in the Spirit, and with this in view, be on the alert with all perseverance and petition for all the saints,
Php_1:4 always offering prayer with joy in my every prayer for you all,
Php_4:6 Be anxious for nothing, but in everything by prayer and supplication with thanksgiving let your requests be made known to God.
Col_4:2 Devote yourselves to prayer, keeping alert in it with an attitude of thanksgiving;
1Ti_4:5 for it is sanctified by means of the word of God and prayer.
Jas_5:15 and the prayer offered in faith will restore the one who is sick, and the Lord will raise him up, and if he has committed sins, they will be forgiven him.
Jas_5:16 Therefore, confess your sins to one another, and pray for one another so that you may be healed. The effective prayer of a righteous man can accomplish much.
1Pe_3:12 "FOR THE EYES OF THE LORD ARE TOWARD THE RIGHTEOUS, AND HIS EARS ATTEND TO THEIR PRAYER, BUT THE FACE OF THE LORD IS AGAINST THOSE WHO DO EVIL."
1Pe_4:7 The end of all things is near; therefore, be of sound judgment and sober spirit for the purpose of prayer.
Well, one sure cannot say that it is not important or effective in the spiritual world. Scripture says for us to pray continually. For me, that comes out of a continual close relationship which I have to work at every single day. I greatly appreciate the fact that His mercies are new every morning when I wake up, but the enemy is right there to begin speaking into my ears and thoughts. It is difficult to learn that I need to take thoughts captive all the time and recognize that all my thoughts are not mine or Father’s.
Obedience to His voice through the Holy Spirit is another matter. We have to humble ourselves and train our spiritual ears to listen. Of course it will always line up with His written word and starts by obeying His commandments (instructions and teachings).