Sanctify them in the truth; your Word is truth.
–John 17:17 (NRSV)–

As for the cowardly, the faithless, the polluted, the murderers, the fornicators, the sorcerers, the idolaters, and all liars, their place will be in the lake that burns with fire and sulphur, which is the second death.
–Revelation 21:8 (NRSV)–

Take care, brothers and sisters, that none of you may have an evil, unbelieving heart that turns away from the living God.
–Hebrews 3:12 (NRSV)–

Do not be mismatched with unbelievers. For what partnership is there between righteousness and lawlessness? Or what fellowship is there between light and darkness?
–2 Corinthians 6:14 (NRSV)–

Whoever wishes to be a friend of the world becomes an enemy of God.
–James 4:4 (NRSV)–

Rebellion is no less a sin than divination,
    and stubbornness is like iniquity and idolatry.
Because you have rejected the word of the Lord,
    he has also rejected you.
–1 Samuel 15:23 (NRSV)–

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Roger Olson, Against Liberal Theology (Zondervan, 2022).

J. Gresham Machen, Christianity and Liberalism (Eerdmans, 2009).