“But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin.”
Hebrews 3:13

In the main verse, he also tells us a characteristic of sin; sin can be deceitful, sin can hardened an individual- a Christian, that means sin can be introduced into a person’s life without ‘loud warning’ signs, only the word of God can detect the manipulation of satan and deceitfulness of sin and quickly guide an individual off that path. The Bible says:
“Neither is there any creature that is not manifest in his sight: but all things are naked and opened unto the eyes of him with whom we have to do.” Hebrews 4:13
You can’t stand against sin’s deception with your physical might, superior mental intellect or careful optical observation, you can only walk on that path of righteousness, that path that is as a shining light, by fellowshipping with the word of God:
“But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.” 1 John 1:7