There are many other verses that teach this same principle. For example, 1 Peter 3:7 tells husbands that their prayers can be hindered by the relationship they maintain with their spouses. This obviously applies to the wife as well. 

In James 5, starting in verse 15, we read of the fact that we are to pray for one another. In verse 16, the Bible says, “Confess your trespasses to one another, and pray for one another, that you may be healed. The effective fervent prayer of a righteous man avails much.” The negative inference here, especially in light of the whole counsel of God, is that the prayers of an unrighteous man do not avail.

If we would turn through the pages of the Old Testament, we would find example upon example of the Lord refusing the sacrifices of the Israelites because of sin in their lives. One of the strongest of such statements is made beginning in Isaiah 1:11. The Bible says…

“To what purpose is the multitude of your sacrifices to Me?” says the Lord. “I have had enough of burnt offerings of rams and the fat of fed cattle. I do not delight in the blood of bulls, or of lambs or goats. When you come to appear before Me, Who has required this from your hand, to trample My courts? Bring no more futile sacrifices; incense is an abomination to Me. The New Moons, the Sabbaths, and the calling of assemblies — I cannot endure iniquity and the sacred meeting. Your New Moons and your appointed feasts My soul hates; They are a trouble to Me, I am weary of bearing them. When you spread out your hands, I will hide My eyes from you; even though you make many prayers, I will not hear. Your hands are full of blood.”
 

This is indeed strong language. Notice especially that it was because of their sins that God says that He will not hear their prayers, though they make many of them.

What does this tell us today? The truth is that our sins are the great separator between God and man. Isaiah 59:1-2 says, “Behold, the Lord’s hand is not shortened, that it cannot save; nor His ear heavy, that it cannot hear. But your iniquities have separated you from your God; and your sins have hidden His face from you.” It should be clear to all that we cannot lead an impenitent sinful life and expect God to fulfill all of the requests we make in prayer (Matthew 7:21; Luke 6:46). We cannot expect God to be at our beck and call, and yet live a life contrary to everything our God is. Sin is a nasty, wicked thing and its consequences are everywhere. Let us never forget that the first consequence we will suffer is the loss of our communion with God—until we confess and forsake those sins (1 Peter 3:12; Proverbs 28:13).

The next time we pray, let us seriously consider what kind of lives we are living. If we have sin in our lives, let us be certain that we “confess our sins to Him, because He is faithful and just to forgive us all sins and cleanse us from all unrighteousness” (1 John 1:9).