We're training to be kings. Kings have to be super lawyers. Lawyer means law-giver. Kings determine the rule for the land, in the ancient world, and the King of Kings became the Way the Truth and the Life, Matt 4:4; so we too have to become the Truth by learning Him. So we can be the 'Kings' under The King of...
So we are boring, sorry. Bible is our rule book, and per Romans 14-15 we have to learn to use it in our own lives, determining the rules for our lives, which means talking about those rules, debating and reasoning out those rules.. just like lawyers do. Sorry.
So when we quote Bible to an atheist or non-Christian, like lawyers we are citing LAW to back up our claims. Or, to explain them. Or, to show there is such a LAW. To show there is a God, He wrote This Book, and here's the proof (citation goes here, or quote, or paraphrase). To the atheist or non-Christian, it's not proof. To us, it is.
For the way to find out if God really exists and who He is, you need to look at the ceiling and ask for proof. Book reading after asking, is the fastest and most conclusive way to get it. God Himself witnesses to whatever is true about Him or From Him. So if this Book is about Him and From Him, as you read it, He will make you KNOW that. For sure.
So golly: it's PERSONAL, and DIRECT. So what proves God to 'you' won't be the same phrasing or connections as what proves God to 'me', etc. That's what makes it conclusive, it's EXclusive. So no one can justify believing based on hearsay.
So once 'you' know that Book is really from God, you'll read and live on and cite from it, as it's your direct and intimate proof: for only God can make that Book intelligible. So the practice of using it as a code of law/rules/guidelines/principles, is what lawyers and diplomats all do. We who are immature Christians, don't know that, but we ape those professionals. It's instinctual, since even though we don't know.. we really are born again, Royal Family of God (potential status for any human, mind you), and as newborns we supernaturally want to do what we are destined to do.. learn and rule.
We do it poorly, okay. Most of us are in the spiritual age of 'two'. Terrible Twos. Sorry.
Of course, most Christians just do it because they ENJOY it, they like the meaning, it helps us understand God (else why bother being trained for kingship), and we like knowing what that Book says. Some among us feel real proud of ourselves if we know words in this Book, especially if they are in the original languages. Just like children, the ones priding themselves on knowing the book. It's a phase one grows out of. Kinda like those priding themselves on their looks or economic status or superiority versus someone else, the immature don't yet UNDERSTAND the words, so grab onto something shallow and meaningless (like status) to motivate learning Words they really don't enjoy. Yet.
Growing pains. Sorry.