John 16:1-4
I have said all these things to you to keep you from falling away. (John 16:1 ESV)
Have you ever known someone who walked away from their faith in Jesus? Perhaps not. Theologians and all manner of people smarter than myself have argued over even the possibility of such a thing for years.
Jesus said it was possible for people to fall away from their faith. He was warning his followers of some of the terrible things to come in hopes that they would maintain faith. He didn't want the trials and afflictions of persecution to drive them away from their belief in him.
It worked. Nearly all of the original twelve disciples went on to give their lives for their belief in Christ. Christianity spread like a flame in a forest. People have continued to believe in Jesus as their savior for nearly two millennia.
In western culture we as Christ followers don't generally face direct physical persecution. Instead we often come up against simmering ridicule, sarcastic academic scrutiny, and posturing political posers. It is sometimes a nearly subconscious or passive aggressive kind of tension that wears away at our faith, if we let it. We have a choice in all things, we choose to let these things push us closer to Christ, or we choose let them erode our faith. If we do succumb to the pressure until the foundations of our faith erode away, we too may one day run the risk of falling away.