Brethren, be followers together of me, and mark them which walk so as ye have us for an ensample. (For many walk, of whom I have told you often, and now tell you even weeping, that they are the enemies of the cross of Christ: Whose end is destruction, whose God is their belly, and whose glory is in their shame, who mind earthly things.)
Be careful of which preachers to whom you listen and "follow" (mark as an example). Just because they call themselves a preacher, does not mean they truly are. Check the Bible for yourself to make sure what they are preaching is true.
That being said, just because some preach the truth, it doesn't mean you should stop checking the scriptures for yourself. Some people begin walking with the Lord, but either stray (they later repent) or no longer walk with Him (no repentance). They may at one time be godly, but turn to their own god which supports their desires of the flesh (vs. 18-19).
As is evidenced through the many headlines of top preachers and Christian leaders confessing their sin and stepping down from their positions, it is possible to stray from or leave your walk with the Lord; however, they are sinners just like the rest of us and if they repent (turn from), they will receive grace. To get an idea of repentance, think about Luke 6:44-47:
For every tree is known by his own fruit. For of thorns men do not gather figs, nor of a bramble bush gather they grapes. A good man out of the good treasure of his heart bringeth forth that which is good; and an evil man out of the evil treasure of his heart bringeth forth that which is evil: for of the abundance of the heart his mouth speaketh. And why call ye me, Lord, Lord, and do not the things which I say? Whosoever cometh to me, and heareth my sayings, and doeth them, I will shew you to whom he is like:
Look at their lives and see if they are producing fruit of righteousness or not. See if they are overcome with "thorns". Do they do what the Lord tells them?
Just because someone quotes scripture, doesn't mean they are following God's commands. You do need to be careful of the people who try to use the Bible to justify their sins. If you go to scripture and look for something to support a view point you can usually find something that, used out of context, will work; however, scripture needs to be taken as a whole. Use scripture to interpret scripture. Read verses in context. Seek (ask for) the Lord's meaning and not your own. In some cases, you may need to go back to the original Hebrew/Greek words and their meanings because translations don't always get it right or can be confusing (I'll post more on this tomorrow).
In short, always be careful of who you "follow" and always check the scriptures for yourself.