There are two ways to look at the Bible. The first is that it is authoritative. The second is that it is not. The latter view is held more widely, for obvious reasons. Only a faithful Christian will acknowledge the authority of the Bible. Every other faith in the world will deny, by word or by deed, that the Bible is authoritative.
If you reject the authority of the Bible, you are free to either agree with it when it's right, or disagree with it when, in your eyes, it's wrong. Let us take homosexuality as the example. It cannot be reasonably disputed that the Bible takes a strong stance against homosexuality. It literally defines marriage as when a man leaves his mother and father and is joined to his wife, and the two become one flesh. Therefore, "gay marriage" is an oxymoron. Furthermore, sexual activity outside of marriage is always wrong, and homosexuality in particular is singled out as an abominable sin. Prior to the death of Christ, it was even punishable by death in Israel, and even after the resurrection, men are commanded to repent of it, lest they also be denied an inheritance in the Kingdom of God.
Now, you might think that's homophobic. You're very silly, but it's possible that you're so committed to the LGBT agenda that you hate any and all dissent from LGBT pride. In that case, you reject the authority of the Bible. And if you truly reject it, you should be ok with just rejecting it. You have no problem rejecting my "homophobic" beliefs while still rejecting them. You don't run around saying "Bible Brain is a queer ministry, Brian himself champions LGBT rights". If you do, you're a liar. In the same way, if you say the Bible is supportive of homosexuality, you either don't know what it actually says, or you're a liar. What you should say instead is "the Bible is against homosexuality, so I am against the Bible".
But many anti-Christians aren't ok with this. Some of them, rejecting Christianity entirely, nevertheless attempt to twist the Bible to support their views. Some of them even claim they, themselves, are Christians. In fact, there are so-called pastors who will passionately assert that the Bible is pro-gay.
Of course, being the very word of God, the Bible is authoritative whether you accept it or not. When the Bible says "thou shalt not", and you do, you are sinning. When the Bible says "thou shalt", and you do not, you are sinning. You can reject its authority until your dying breath, but after you take that breath, you stand before its Author, and He will judge you, and you will be condemned for every time you rejected it. But it gets far worse for those who do not reject its authority. Rather, each attempt to use the Bible in support of their views is a confession that if they were right, it would be a genuine support.
Think of it this way: If you cite some random religious person in support of your views, it's meaningless even in context. In fact, outside of Scripture, even the most radical LGBT activist will admit that religious people, particularly throughout history, have been quite homophobic. The only way to separate the Bible from the religious people who wrote it, then, is to admit that it is separate. That is, it is more than just some random religious writing. It is the very word of God.
But being the word of God, it has authority over all. What it says is truth. When you acknowledge this, you not only accept its authority over yourself, but you become a major hypocrite when you go on to twist it for your own ends. The result? The New Testament indicates it will be worse for you than for an unbeliever (e.g. Luke 12:47-48).
But even in the Old Testament, God does not take too kindly to those who acknowledge His authority yet refuse to submit to it. In Psalm 40:16-23, we read "But to the wicked God says: “What right have you to declare My statutes, Or take My covenant in your mouth, Seeing you hate instruction And cast My words behind you? When you saw a thief, you consented with him, And have been a partaker with adulterers. You give your mouth to evil, And your tongue frames deceit. You sit and speak against your brother; You slander your own mother’s son. These things you have done, and I kept silent; You thought that I was altogether like you; But I will rebuke you, And set them in order before your eyes. “Now consider this, you who forget God, Lest I tear you in pieces, And there be none to deliver: 23 Whoever offers praise glorifies Me; And to him who orders his conduct aright I will show the salvation of God.”"
God does not even want His covenant in the mouth of those who refuse to abide by it! If you're running around defending that which He hates, what right have you to claim His promises? If you support what He despises, how do you have the audacity to even cite His commands? And if you want His salvation, how do you so comfortably remain in the quagmire He seeks to save you from?
In the end, it all comes down to this: If you believe the Bible is authoritative, don't bother twisting it to conform to your own sin. Rather, twist yourself to conform to it. If you don't believe it's authoritative, you're wrong, but at least be consistent about it. In both scenarios, basically, don't be a hypocrite. Either accept the Bible as it is, or reject the Bible as it is.