SCRIPTURE Hebrews 12:14–15 “Follow peace with all men, and holiness, without which no man shall see the Lord: Looking diligently lest any man fail of the grace of God; lest any root of bitterness springing up trouble you, and thereby many be defiled;” 

COMMENTARY Note that “peace with all men, and holiness” are requirements to spending eternity with God and these occur after first profession.  These can only be accomplished by submitting to the leading of the Holy Spirit, something the doctrine of eternal security says is not essential to salvation.  Furthermore, it states quite clearly, in context, that one may fail (Greek hystereō) the grace of God.  Failing means to “fail to reach the goal”.