Which concepts of the Bible are mostly misunderstood?

The concept of rightly dividing the Word of Truth is certainly one of the most misunderstood.

In "rightly dividing" the scripture, the Bible becomes a source of wisdom, instead of being a source of confusion and contradiction.

2 Timothy 2:15 Study to show thyself approved unto God, a workman that needs not to be ashamed, rightly dividing the word of truth.

The few examples in the table below illustrate how one separates Israel (the Jews), from the Body of Christ according to this verse:

1 Corinthians 10:32 Give none offence, neither to the Jews, nor to the Gentiles, nor to the church of God [Body of Christ]:

Israel is not reckoned among the nations (Num.23:9). God works with Israel in a different program to Gentiles. The church today has not replaced Israel, physically or spiritually! God has provided the Gentiles with a new (different) program based on the doctrine provided to Paul in his epistles. This is the grace program in which God is operating today. Jews that believed in the gospel of their day and trusted in God are saved unto the Kingdom. Gentiles that believe the grace gospel and have become regenerated in spirit form part of the Body of Christ. The remaining humanity who has not responded in faith to God form part of the last column.

If one studies the Bible by rightly dividing the Word, keeping the first two columns separate, the bible will become clear and revelatory. This concept is critical to learn if one is to understand the Bible in its proper context.

(The chart below is a small cross section of right division. It does not represent right division in its full context. This is just a sample for sake of reference.)