Dealing With Disagreements Concerning Scriptural Doctrine

All scripture is inspired of God, both Old, and New Testaments. It was perfectly composed, precept upon precept, line upon line, and therefore should be studied and "rightly divided" if we, as Christians, are to grow in grace, be effective disciples, and be approved by God.
"All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness...." 2 Tim.3:16."But the word of the LORD was unto them precept upon precept, precept upon precept; line upon line, line upon line...." Isaiah 28:13."Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth."  2 Tim.2:15. 
There is much doctrinal disagreement between professing "Christian" Denominations and even within Denominations as well as in individual churches. Some of those differences include whether Salvation is totally by grace through faith or includes some measure of good works. Another is whether predestination springs from God's eternal foreknowledge or foreknowledge springs from predestination. Others concern tithing, marriage, sin, prophecy, baptismal regeneration, a literal or figurative hell... and many other doctrines. "Doctrine is simply a word referring to the primary, foundational subjects of God's word.
Where one is uncertain of the interpretation or understanding of a scripture or doctrine, or when there appears to be a contradiction between two scriptural texts, one must go with the preponderance of evidence and which position most clearly harmonizes with the whole counsel of God. It is always proper to consider which of two opposing, doctrinal positions is most compatible with the revealed mind of God in all the rest of scripture. Every true Christian knows that no two scriptures contradict each other. So, whatever a verse means, that meaning will be discovered in the light of all scripture.
Bible commentaries are fine, but they are not holy scripture. All commentaries were written by faulty men who wrote what they believed was true, but no man is "perfectly" correct on everything he believes. Only Jesus, the Living Word of God, was perfectly perfect. The Bible throws more light on commentaries than commentaries do the Bible.
"For I have not shunned to declare unto you all the counsel of God. Take heed therefore unto yourselves, and to all the flock, over the which the Holy Ghost hath made you overseers, to feed the church of God, which he hath purchased with his own blood. For I know this, that after my departing shall grievous wolves enter in among you, not sparing the flock. Also of your own selves shall men arise, speaking perverse things, to draw away disciples after them.  Therefore watch, and remember, that by the space of three years I ceased not to warn every one night and day with tears. And now, brethren, I commend you to God, and to the word of his grace, which is able to build you up, and to give you an inheritance among all them which are sanctified." Acts 20:27-32. As a general rule, you are safe and correct to simply interpret every scripture to mean exactly what it says, within its context. If there are extenuating circumstances, types, illustrations and proverbs or hyperbole, they must conform with all the rest of scripture. The word of God does not contradict itself, exaggerate or lie.