There is nothing more dangerous than being in the comfort zone.

1 Corinthians 10:12 KJV
Wherefore let him that thinketh he standeth take heed lest he fall.

Now the Word of God constantly reminds us that while we exist in this world we are in a constant battle against our flesh,  the worldly principalities, powers, rulers of the darkness, spiritual wickedness in high places etc. (Ephesians 6:12). So it is our duty not to be too comfortable but to always prepare ourselves for any kind of ammunition that is targeted at us (1 Peter5:8).

It is so easy for someone who has become too comfortable to lose notice of their own downfall (2 Samuel 12: 5-9). And even spiritually it is so easy for other spirits to take over someone who has become too comfortable. "1 John 4:6" Speaks about the SPIRIT OF ERROR that is where you start finding tweaked teachings or teachings that have gone soft on worldliness because people have become too comfortable forgetting now that they are pleasing other people more than the Almighty God.

Let us remember who we are, where we come from and where we are going in order to watch and stay sober.

1 Thessalonians 5:6 KJVI
Therefore let us not sleep, as do others; but let us watch and be sober.