In Christ, we have a firm foundation upon which to stand on. When things get rough or the seas of life get stormy, all we need to do is look to Christ and His Word to be reminded that in Him we have a firm foundation that will not be shaken. 

"...if we are faithless, He remains faithful." (2 Timothy 2:13)

A person's faithlessness (i.e. abandonment of the faith does not affect God's faithfulness (i.e. His commitment to His mission to save sinners).

Sin can't enslave a person who is utterly confident and sure and hope filled in the infinite happiness of life with Christ in the future (John Piper).

So we do not lose heart. Though our outer self is wasting away, our inner self is being renewed day by day. For this light momentary affliction is preparing for us an eternal weight of glory beyond all comparison, as we look not to the things that are seen but to the things that are unseen. For the things that are seen are transient, but the things that are unseen are eternal (2 Corinthians 4:16-18)

For I consider that the sufferings of this present time are not worth comparing with the glory that is to be revealed to us (Romans 8:18)

Therefore, since we are surrounded by such a great cloud of witnesses, let us throw off everything that hinders and the sin that so easily entangles, and let us run with perseverance the race marked out for us.  Let us fix our eyes on Jesus, the author and perfecter of our faith, who for the joy set before him endured the cross, scorning its shame, and sat down at the right hand of the throne of God. (Hebrews 12:1-2 NIV1984)