Hebrews 3:12-14 (KJV)
12 Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.
13 But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin.
14 For we are made partakers of Christ, if we hold the beginning of our confidence stedfast unto the end;

Our confidence, believe and faith is in Jesus Christ. When we heard the gospel of Christ we believed and by this we became partakes of Christ. Now as we follow Jesus we need to know how we protect our self so we are not deceived by sin. Here we are warned as in many other places. Because if we sin and then keep on sinning our heart hardens and we become num to the conviction of the Holy Spirit, thinking it is ok. We then let unbelief creep in which then results in the departure from faith in Jesus Christ.
In Hebrews 3:10 (KJV) it says “Wherefore I was grieved with that generation, and said, They do alway err in their heart; and they have not known my ways.” GOD is grieved when our heart goes astray. To help us to stay on the straight and narrow “Matthew 7:14 (KJV) Because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it.” We need to know the LORD GOD’s ways and hold fast to Jesus and our faith in Him. “Hebrews 3:6 (KJV) But Christ as a son over his own house; whose house are we, if we hold fast the confidence and the rejoicing of the hope firm unto the end.” The way we learn and know His ways is through the Word of God. In verse 13 of Hebrews 3 we are told to exhort one another every day. This is one of the things that helps not to be deceived by sin. Now we need to understand this that if we sin (miss GOD’s mark) we need to call on Jesus and repent “1 John 1:7-10 (KJV) 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. [8] If we say that we have no sin, we deceive ourselves, and the truth is not in us. [9] If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness. [10] If we say that we have not sinned, we make him a liar, and his word is not in us.” One thing that demonstrates us walking in the light is by us fellowshipping, spending time with other followers of Jesus. Let us also be assured that GOD’s love and mercy is so great that even if we stray and walk away there is hope “Hosea 14:4 (KJV) I will heal their backsliding, I will love them freely: for mine anger is turned away from him.” But let us not tempt GOD and love Him instead of this world and sin.

Therefore be encouraged to take heed of ourselves daily by: exhorting each other, siting at Jesus Christ feet, reading/studying/knowing the Word of God and following Jesus Christ as it is written in Luke 9:23 (KJV) “And he said to them all, If any man will come after me, let him deny himself, and take up his cross daily, and follow me.”