1) A Christian could have a preconceived notion that ordinary Christians can't understand the Bible. A believer who is convinced that the Bible is only for church and only to be explained by the pastor has erected a barrier to understanding. God intends the Bible to be for all believers. God commends the believers in Berea, stating, "Now these were more noble-minded than those in Thessalonica, for they received the word with great eagerness, examining the Scriptures daily to see whether these things were so" (Acts 17:11). Far from relegating Scripture to the church setting alone, these believers went home and studied the Bible to make sure the preacher was instructing correctly.
2) A Christian could be limited due to his intellectual ability. God has not given every individual the same abilities or opportunities. Someone with more education and a higher reading level is better equipped to understand anything he reads, including the Bible. This does not mean, however, that a less educated person cannot understand the Bible. "The unfolding of Your words gives light; it gives understanding to the simple" (Psalm 119:130). If the wording of the King James Version is restrictive, a believer might consider using a reliable modern translation, such as the New American Standard Bible or the English Standard Version.
3) A Christian might not be using profitable reading techniques. I have discussed this elsewhere, but a few general guidelines are that a reader should pause to absorb what he has read, should summarize content in his own words, should read passages within their context, and should approach the Bible systematically.
4) A Christian could struggle due to limited Biblical background. Understanding of the Bible builds over time. The truths found throughout the Bible interconnect with and support each other. As a reader gains understanding of one portion of the Bible, he will be better prepared to understand other portions. As his understanding of those other portions then increases, he will be better equipped to increasingly understand the initial portion. Understanding the Bible is an ongoing process that constantly contributes to increasing understanding. Even new Christians can have some understanding. "Like newborn babies, long for the pure milk of the word, so that by it you may grow in respect to salvation" (I Peter 2:2).
5) A Christian might be troubled by his inability to understand certain parts of the Bible. Some parts are harder to understand than others. Peter describes Paul's writings: "In which are some things hard to understand" (II Peter 3:16). The Bible deals with eternal and divine concepts; mere mortals won't be able to understand completely. Limitations in understanding some portions of Scripture should not prevent a believer's continued sincere attempts. In some cases, a Christian might simply need to set aside a certain passage and focus elsewhere. "But solid food is for the mature, who because of practice have their senses trained to discern good and evil" (Hebrews 5:14).
6) A believer might struggle to understand because he has "become dull of hearing" (Hebrews 5:11). The author of Hebrews rebukes certain Christians: "For though by this time you ought to be teachers, you have need again for someone to teach you the elementary principles of the oracles of God, and you have come to need milk and not solid food" (Hebrews 5:12). The problem is not with the Bible, but with the reader.
There are indeed people who can't understand the Bible. "But a natural man does not accept the things of the Spirit of God, for they are foolishness to him; and he cannot understand them, because they are spiritually appraised" (I Corinthians 2:14). This ought not to be true of a Christian, who has the Spirit of God to enable him to understand spiritual truth (John 16:13). A failure to reasonably understand the Bible can be an indication of carnality. While Christians have a spiritual nature, they can allow their carnal natures to squelch their spiritual natures; when carnality rules, spiritual discernment wanes.
Carnality can be expressed through a love of the world. "Do not love the world nor the things in the world" (I John 2:15). "Do you not know that friendship with the world is hostility toward God?" (James 4:4). An obsession with, desire for, and following of the world's lifestyle, philosophy, and pursuits creates a great barrier to spiritual discernment by putting a believer in opposition toward God.
Carnality can be expressed through distraction by earthly things. Life contains necessary "distractions," such as family and work; life can also be filled with unnecessary, chaotic, and detrimental distractions, like technology, entertainment, and activities, which quench spiritual appetites and sensitivity. II Timothy 3:4 refers to those who are "lovers of pleasure rather than lovers of God." No man can effectively love both (Matthew 6:24).
Carnality can be expressed through resistance to God. A believer can "quench the Spirit" of God who wants to give him understanding (I Thessalonians 5:19). A believer can fight with God over some issue, thus introducing a barrier. "God is opposed to the proud. . . . Therefore humble yourselves under the mighty hand of God" (I Peter 5:5-6). Un-confessed sin also introduces an obstacle (I John 1:6-9).
The Bible is powerful and effective (Hebrews 4:12), and God intends for it to be a source of light and understanding (Psalm 119:105). A believer who struggles to understand the Bible should examine these potential areas of limitation and should earnestly ask the Spirit to aid his understanding.