The devil does not come to you with red horns and a pitchfork. He comes to you as everything you've ever wanted. That may sound cliché to you. And if it does, good. Keep whatever told it to you. It's been feeding you great wisdom. But as cliché as that is, it cannot be emphasised enough.
When unwise people think of the devil, they expect to be able to recognise him as easily as one might be able to spot a polar bear in the desert. But my brethren, we are not dealing with a fool as our adversary. We are dealing with a 6,000 year old menace. He has absurd amounts of deceptive power, and he is well aware of how to use it to trip you up. Satan is a brilliant deceiver.
He is not alone. In a sense, Satan is just a king. Sort of like how we might attribute a military operation to a leader. We might say Obama killed Bin Laden, for example, even though he wasn't even on site when Bin Laden was killed. There was even one hilarious meme during his presidency that I hope will make the point: "Obama's approval ratings are so low, he's thinking of killing Bin Laden again."
So, things done with the authority of a ruler may not actually be done by that ruler. It may even be unlikely that you, personally, will ever directly encounter Satan. Nevertheless, in this spiritual war, he is a king against whom we fight, and his forces bear his name. Now, just as Satan himself has great deceptive power, the Bible tells us that his servants also do. In fact, Paul tells us that Satan can disguise himself as an angel of light, and his servants can disguise themselves as servants of righteousness.
So what if one of them is preaching in your church? What if one of them is asking for your vote this election season? What if one of them is preaching to you from a Facebook page you follow?
Ultimately, you can't just trust someone because they claim to be a Christian. Every heretic in the world claims to be preaching either the truth from God, or even a truth better than God's. Someone can claim to be a Christian, but the myth that the devil cannot enter a church is propagated by the devil himself. What swindler doesn't know how to smile with a twinkle in his eye? What trickster can't make you look left while he does something on the right? If a magician can disappear in a puff of smoke, imagine what Satan and his forces can do with their supernatural advantages.
So what's the solution? Well, to rely on the one being who's smarter than Satan, of course. Satan may be a clever trickster, but he's never going to be so smart that he can outwit the Holy Spirit. God gave us His inspired word for the very purpose of opposing Satan. If you rely on God's word, you will not easily be taken by surprise. For sure, you can still err. After all, just because God is perfect doesn't mean you are. But He has given us everything we need to hold out against the lies of the devil. Therefore, test everything and hold on to that which is good. If you hear something, don't just swallow it whole. Take it with a pinch of Scripture. And more than just one pinch. No matter who says something, do not assume it is true. Good teachers can err, and bad teachers can deceive, but the Lord will never lead you astray.