God's Word, the Bible, is truth. It doesn't just contain truth. It is truth. And because it is truth, flowing from the mind and heart of an ever-gracious God, it is the kind of truth that sets people free.
In our current era, the surrounding culture is exerting pressure as never before upon evangelicalism to change and compromise its message – to adapt its theology to accommodate the ebb and flow of what is popular and to the opinion that has consensus. I've seen tweeted way too many times lately that Christians "are on the wrong side of history" on certain social issues.
What secular thinkers (as well as "progressive" evangelical, emergent, and liberal Christian thinkers) fail to understand is the power of our basic presupposition. IF the Bible is indeed a special revelation from God – a body of divinely revealed truth (which is a completely reasonable framework) then we don't have the option of dissecting it to determine which parts are to be believed.
At the same time, we aren't called to remain in a spirit of bitterness about opposing views. When we aren't careful with our spirits, we wind up misrepresenting the very nature of grace in how we choose to stand for truth. For example, most of the time when I hear Christians repeat popular catch phrases like, "love the sinner, hate the sin," I know that the person saying it presumes their hearer understands the meaning behind both phrases. Unfortunately, we rarely actually communicate what we think we mean.