Bible has internal consistency from "summary" of Christian Apologetics by Norman L. Geisler

The Bible's internal consistency is remarkable. Its unity can be seen throughout the Old and New Testament, although written by different authors in very different times and circumstances.

Scripture is internally consistent in that it reveals a unified message on Christian doctrine; it explains moral truths consistently and teaches practical living and discipleship.

All of the books of the Bible teach similar doctrines - faith in Christ, love, forgiveness, moral principles, devotion to God, justice etc. thus showcasing its internal consistency.

The consistency of biblical teaching cannot be denied, and this establishes confidence that the scripture is from God and directed to us.

The truth found within the Bible brings glory to God by revealing his love for humanity that will last through eternity.

The logical guidelines associated with the Scripture mean that it follows a certain set of rules for rational thought which gives strength to its internal consistency.

We can trust the Bible because whatever it says has one common theme: loyalty to God and respect for others.

An examination of its teachings on topics such as God, Jesus, the Holy Spirit, man, sin and redemption all agree and fit together like a jigsaw puzzle forming a cohesive picture.

Numerous prophecies have been fulfilled in history, people’s lives have been changed, and examples abound of modern-day miracles which serve as evidence of the Bible's divine inspiration.

The spiritual aspect of the Scriptures testifies to its authenticity and the presence of insight within it; proving its credibility and providing further evidence of its internal consistency.