2Tim3:16 All Scripture is inspired by God and is useful to teach us what is true and to make us realize what is wrong in our lives...(17) God uses it to prepare and equip his people to do every good work. NLT
When a man has a dislocated or fractured bone, one of the medical examinations recommended is an X-ray. The X-ray machine would detect what is wrong inside the person and what needs correction. The word of God is God's x-ray to make us realize what is wrong in our lives and what need correction.
The scripture above said all scripture is inspired by God and is useful to teach what is true. Don't be selective when you're studying your bible, I understand the dichotomy of old and new testament in the bible but whether we like it or not, there are truths that are trans dispensational from Genesis to Revelation and are relevant today.
Let the Holy Spirit teach you what he want you to learn from God's word. God want to use His word to groom you and make you the kind of man He want you to become. Stop being selective, when God is teaching you a relevant truth from the scriptures, accept it and change. The word is God's tool that can make your life better, take advantage of it.
Father, I receive the word with gladness, my life shall conform to God's word henceforth In Jesus name.