If you read the Bible with a dead spiritual nature, and don’t understand it, then become “born again
“Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God. Which things also we speak, not in the words which man's wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual. But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.” 1 Corinthians 2:12-14
There are several factors that sometimes make the Bible hard to understand. First, there is a time and culture difference. Depending on what part of the Bible you are studying, there is between 3400 and 1900 years between when the Bible was written and us today. The culture in which the Bible was written was very different from most of the cultures that exist today. The actions of nomadic shepherds in 1800 B.C. in the Middle East often do not make much sense to computer programmers in 21st-century America. It is crucially important that, when trying to understand the Bible, we remove the 21st-century “lenses” we have and try to recognize the culture in which the Bible was written.
Second, there is the fact that the Bible contains different types of literature. The Bible contains history, law, poetry, songs, wisdom literature, prophecy, personal letters, and apocalyptic literature. Historical literature must be interpreted differently from wisdom literature. Poetry cannot be understood in the same way as apocalyptic writings. A personal letter, while having meaning for us today, may not have the exact application to us as it did to the person(s) to whom it was written. Recognizing the fact that the Bible contains different genres is key in avoiding confusion and misunderstanding.
Third, we are all sinners; we all make mistakes (Ecclesiastes 7:20; Romans 3:23; 1 John 1:8). As much as we strive not to read our preconceived biases into the Bible, it is inevitable that we all occasionally do so. Sadly, at some point everyone misinterprets a Scripture due to a presupposed understanding of what a particular Scripture can or cannot mean. When we study the Bible, we must ask God to remove the biases from our minds and help us interpret His Word apart from our presuppositions. This is often a difficult step to take, as admitting presuppositions requires humility and a willingness to admit mistakes.
By no means are the three steps outlined above all that is needed to properly understand the Bible. Entire books have been written on how to interpret the Bible. Biblical hermeneutics is the science of biblical interpretation. However, the three steps above are an excellent start in how to understand the Bible. We must recognize the cultural differences between ourselves and the people in Bible times. The different genres of literature must be taken into account. We must strive to allow the Bible to speak for itself, not allowing our presuppositions to determine the interpretation.
Trying to understand the Bible can sometimes be a difficult task, but with God’s help, it is possible. Remember, if you are a believer in Jesus Christ, God's Spirit indwells you (Romans 8:9). The same God who "breathed out" Scripture (2 Timothy 3:16-17), is the same God who indwells you and will open your mind to the truth and understanding of His Word if you rely on Him.
Notwithstanding what is stated above, the Bible is NOT an intellectual exercise, it is a spiritual one. It is in many ways written in spiritual code, deciphered for men by the Holy Sprit which is what makes it a spiritual exercise.
For this reason those who are engaged in an intellectual study and interpretation of scripture often get it wrong. This is not to say that God will always make it easy. God desires us to search His Word and to fully explore it, in this regard one draws closer to the Lord as he reveals perpetual truths. Understanding the Bible is not always easy, but it is always eminently rewarding.