Settling every Bible based question or studying every Bible based topic can hardly be resolved with a single verse every time, but there are times when a single verse is so clear and concise in what is being said, the point cannot be missed by any honest Bible student.
For example, take the question and topic of apostasy … or falling from the grace (i.e. salvation) of God. 1 Corinthians 10:12 notwithstanding, 2 Peter 2:21 plainly says, of those who enjoyed the liberty of God’s freedom, “For it would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment delivered to them.”
If one believes it is impossible to turn from God after one has turned to God, then he or she needs to learn the lesson taught by God in 2 Peter 2:21.