Verse 16 gives us a clue in preventing deception. God says, "Take heed to yourselves." What does this tell us? This means pay attention! Take care. Guard yourself. Watch out. We cannot just skip our way into the Kingdom of God. It will take a great deal of effort.
"Take heed to yourselves"—what we are allowing yourself to do; what we are getting involved in; who our friends are, how much time we are spending on this, that, and the other thing. How close is our relationship with God? That is what we must watch and take heed of.
God wants us to jealously protect our spiritual growth. Once we develop a trait of godly character, we should never give it up! Guard that eternal life that has been built within us—by God's grace and our yieldedness.
Most of the time, people become deceived because they are not watching what is going on. They are in "la-la land." Something intrudes into their lives, and they follow it because they have no strength to resist. They have not been watching themselves.
God's way requires constant vigilance. "Watch and pray always," Jesus says. Our guard has to be up against deception all the time. We have to have our antennas out, making sure that what we hear is true. Thus, if we become deceived, whose fault is it? Is it God's or ours? God says, "Take heed to yourself." He has shown us the way to live. He has revealed it to us. He has left nothing hidden that we need to know. So whose fault is it, if we get tripped up? We are not going to be able to accuse God of it. So who is left? We are.