I believe every word written in Scripture is true, but this does not give me the authority to interpret the Bible however I like in every situation. Rather we must all have an interpretive guide, otherwise we cannot be certain that of the truth.
The Bible itself says that interpretation is not to come from ourselves alone:
Know this first of all, that there is no prophecy of scripture that is a matter of personal interpretation for no prophecy ever came through human will; but rather human beings moved by the holy Spirit spoke under the influence of God. -2 Peter 1:20-21It also says we need an authority to help us interpret the Bible correctly:
Philip ran up and heard him reading Isaiah the prophet and said, "Do you understand what you are reading?" He replied, "How can I, unless someone instructs me?" So he invited Philip to get in and sit with him. - Acts 8:30-31The Bible also says that some parts are hard to understand, as Peter says when writing about Paul's epistles:
And consider the patience of our Lord as salvation, as our beloved brother Paul, according to the wisdom given to him, also wrote to you, speaking of these things as he does in all his letters. In them there are some things hard to understand that the ignorant and unstable distort to their own destruction, just as they do the other scriptures. - 2 Peter 3:15-16The Bible is a collection of ancient texts with different audiences, authors, messages, literary styles, objectives, and styles. We have to study it intently and have a proper hermeneutic, that is, a proper way of interpreting the Bible. If we don't have this, then we can easily find ourselves committing interpretive errors. While the bible might be inerrant, we are not. With this is mind, Jesus set up the Catholic Church to help us.
In light of the Church's teaching, Fr. Barron has some great comments on violence in some difficult passages in the Bible: