Hebrews 3:11-15

So I sware in my wrath, They shall not enter into my rest.) Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God. But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin. For we are made partakers of Christ, if we hold the beginning of our confidence stedfast unto the end; While it is said, To day if ye will hear his voice, harden not your hearts, as in the provocation.

We must remain faithful until the end. We should try to help each other to stay close to the word of God and not stray from the truth. We must not harden our hearts to what God has for us to do and the direction that he wants us to go. If you fall away it will not be pretty for you in the end.