In a recent blog post John Piper was quoted as saying, "When I am anxious that I may make shipwreck of faith and fall away from God, I battle unbelief with the promise, “He who began a good work in you will complete it unto the day of Christ” (Philippians 1:6). “He who calls you is faithful. He will do it” (1 Thessalonians 5:23). “He is able for all time to save those who draw near to God through him, since he always lives to make intercession for them” (Hebrews 7:25)."
So what does it mean to 'fall away'? I assume that what Piper means by 'falling away' is to actively resist growth in the grace of sanctification through sins of omission or sins of commission. It certainly cannot be forensic in nature for that is not dependent upon our works but upon the sovereign declaration of God in Christ.
Therefore even if we would fall away from God and make a shipwreck of faith (God forbid), these verses still remain true! For a "falling away from God" does not hinder one's position in Christ. God's intentions to save whether in justification, sanctification or glorification are not thwarted. He does not change in relation to our sinful blights. He remains the same. There remains mountains of mercy through the covenantal love of God purchased up by Christ.
For those who have made a shipwreck of faith God's love remains! They have not outrun his love, for nothing is able to separate us from the love of God in Christ Jesus our Lord, not even our failures.