The obstacles to our prayers are many and the following list is not exhaustive :

The ignorance of the only Mediator between God and men, the Lord Jesus Christ, and consequently of prayer in His Name (John 15:7).

John 15 : 7 « 7If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you. » KJV

The refusal to do what is pleasing to God and requests that are not according to His will (1 John 3:22, 5:14-15).

1 John 3 : 22 « 22And whatsoever we ask, we receive of him, because we keep his commandments, and do those things that are pleasing in his sight. » KJV

1 John 5 : 14-15 « 14And this is the confidence that we have in him, that, if we ask any thing according to his will, he heareth us: 15And if we know that he hear us, whatsoever we ask, we know that we have the petitions that we desired of him. » KJV

Lack of faith (Matthew 21:22) or mutual agreement (Matthew 18:19).

Matthew 21 : 22 « 22And all things, whatsoever ye shall ask in prayer, believing, ye shall receive. » KJV

Matthew 18 : 19 « 19Again I say unto you, That if two of you shall agree on earth as touching any thing that they shall ask, it shall be done for them of my Father which is in heaven. » KJV

Vagueness in the formulation of our requests (Luke 18:40-41), or even the absence of a request (James 4:2).

Luke 18 : 40-41 « 40And Jesus stood, and commanded him to be brought unto him: and when he was come near, he asked him, 41Saying, What wilt thou that I shall do unto thee? And he said, Lord, that I may receive my sight. » KJV

James 4 : 2 « 2Ye lust, and have not: ye kill, and desire to have, and cannot obtain: ye fight and war, yet ye have not, because ye ask not. » KJV

Lack of perseverance in prayer (Romans 12:12; Ephesians 6:18).

Romans 12 : 12 « 12Rejoicing in hope; patient in tribulation; continuing instant in prayer. » KJV

Ephesians 6 : 18 « 18Praying always with all prayer and supplication in the Spirit, and watching thereunto with all perseverance and supplication for all saints. » KJV

But we could also add to this list:

Sin. Our fallen nature causes much damage to our prayers (Isaiah 59:1-2; James 4:8).

Isaiah 59 : 1-2 « 1Behold, the LORD’S hand is not shortened, that it cannot save; neither his ear heavy, that it cannot hear: 2But your iniquities have separated between you and your God, and your sins have hid his face from you, that he will not hear. » KJV

James 4 : 8 « 8Draw nigh to God, and he will draw nigh to you. Cleanse your hands, ye sinners; and purify your hearts, ye double minded. » KJV

Idols of the heart. What is an idol (Ezekiel 14:3)? An idol is anything a man has placed above God (spouse, children, social status, work, hobbies, etc.). Every man who put these things before God is idolatrous in His eyes. God first !

Ezekiel 14 : 3 « 3Son of man, these men have set up their idols in their heart, and put the stumblingblock of their iniquity before their face: should I be inquired of at all by them? » KJV

Lack of forgiveness and resentment (Mark 11:25). A spirit of resentment prevents God from answering our prayers. The refusal to forgive hinders our prayers, blocking our relations with God and with others.

Mark 11 : 25 « 25And when ye stand praying, forgive, if ye have ought against any: that your Father also which is in heaven may forgive you your trespasses. » KJV

Greed (Proverbs 21:13). God tells us that if we close our ears to the cries of the poor when they call us for help, He will also close His when we cry to Him to ask for His help. Greed hinders our prayers. On the other hand, if we help those in need, God assures us that our prayers will be answered (Proverbs 11: 25 and 22: 9). Likewise, if we are generous to the Lord, He promises to provide abundantly for our needs (Malachi 3:10-11; Luke 6:38).

Proverbs 21 : 13 « 13Whoso stoppeth his ears at the cry of the poor, he also shall cry himself, but shall not be heard. » KJV

Proverbs 11 : 25 « 25The liberal soul shall be made fat: and he that watereth shall be watered also himself. » KJV

Proverbs 22 : 9 «9He that hath a bountiful eye shall be blessed; for he giveth of his bread to the poor. » KJV

Malachi 3 : 10-11 «10Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the LORD of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it. 11And I will rebuke the devourer for your sakes, and he shall not destroy the fruits of your ground; neither shall your vine cast her fruit before the time in the field, saith the LORD of hosts. » KJV

Luke 6 : 38 « 38Give, and it shall be given unto you; good measure, pressed down, and shaken together, and running over, shall men give into your bosom. For with the same measure that ye mete withal it shall be measured to you again. » KJV

Bad relations between spouses (1 Peter 3:7). To mistreat one’s spouse is an obstacle to the prayer, just as anything that would depart from the will of God in a couple’s life.

1 Peter 3 : 7 « 7Likewise, ye husbands, dwell with them according to knowledge, giving honour unto the wife, as unto the weaker vessel, and as being heirs together of the grace of life; that your prayers be not hindered. » KJV

The feeling of guilt or unworthiness. It makes us believe that God has grievances against us and prevents us from believing that we can approach Him with confidence, in prayer. If we want to approach God in prayer, we must grasp this truth of Romans 8, that there is no longer any condemnation for those who are in Jesus Christ!

God no longer wants us to remind Him of the sins He has already forgiven. By His sacrifice on the Cross, Christ has already made us perfect in Him.

Romans 8 : 1 « 1There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit. » KJV

Wrong motivations. The Bible explains that if we have wrong motivations, our prayers are hindered (James 4:3). But if our motivations are good, then we can count on the Lord to provide for our daily needs.

James 4 : 3 « 3Ye ask, and receive not, because ye ask amiss, that ye may consume it upon your lusts. » KJV

Praying is not trying to get God to do what we have decided, but seeking His will for us, relying on the righteousness of Christ and our rights as children of the Kingdom.