The first great principle of Bible study is a reliance on the Holy Spirit to guide you.
There are other important principles. One is to let Scripture interpret Scripture rather than letting tradition interpret. Another important principle is to accept the plain reading of Scripture. Sometimes that is literal; sometimes it is not. Genesis 1 and 2 is a case where the plain reading is literal. Some (perhaps well-meaning) Christians have attempted to find millions or even billions of years between the first and second verses of Genesis. It is my contention that there is no Biblical evidence for that nor is there any other kind of evidence either.
The problem arises when Christians try to help God out by trying to contrive a way to make the Bible match current “scientific” understanding. I placed quotes around science because it appears to me that this so-called science is not very scientific. It seems apparent to me that this science has been tainted by the need to retain tenure in teaching positions and also in keeping government grant money flowing. As Christians, we are always on solid footing when we hold fast to the idea that it is science which must conform to Scripture not vice versa.
The plain reading of Genesis 1 gives absolutely no indication that there was a long period of time between the first two verses. I am well aware of the attempts to (in my estimation) twist a couple of words in verse two. Those attempts do not hold up under the scrutiny of Hebrew linguists. I am also aware of an unfortunate translation in the KJV in Genesis 1:28 which adds nothing to the discussion. This idea of inserting long ages is a pure invention to attempt to make the Bible more palatable to the world. The Bible does very well on its own.
Many Christians who have not thought this through are simply of the opinion that this is not a significant issue. It is very, very significant. The insertion of long ages into Genesis 1 casts doubt upon Exodus 20:11 as well as Mark 10:6, thus doing violence to the Ten Commandments and the very words of Jesus. In Genesis 1:31 God declared the newly completed creation to be “very good”. Inserting long ages would mean that God declared death, disease, etc. to be very good.
Most importantly, the insertion of long ages between the first two verses of Genesis renders the sacrificial death of Christ unnecessary. If disease, suffering, and death occurred before the Fall of Man and the ensuing curse then what is the need for a seed of the woman to crush the head of the serpent and redeem fallen mankind? You are correct, there would be no need. Death before sin renders much of the rest of the Bible unintelligible. If death preceded Adam and Eve’s rebellion then what happens to the clear doctrine of Christianity concerning the Fall of Man? If disease, death, suffering, and curse were my lot before Adam or I ever sinned, then grace is not really grace. If death was in place before sin, then God’s commandment with consequences in Genesis 2:16-17 is nonsensical at best but more likely deceitful. If death came before sin, then mercy is really not mercy at all. If death came before sin, why would we need countless animal sacrifices on Old Testament altars? If death came before sin, why would we need a once-for-all sacrifice on Calvary’s Cross? Enemies of the Cross have drawn this out to its logical conclusion. It is long past time that Christians do the same. Death before sin is dangerous beyond comprehension.