I will say that if our faith apprehends the sealing of the Holy Spirit, we will have an everlasting faith.
If someone ceases to have faith, they are no longer saved.
Ephesians 2:8-9
Romans 5:1-2.
We are saved by grace through faith; we have access by faith into this grace wherein we stand.
Therefore if we cease to have faith, we cease to be recipients of grace; and we are no longer saved.
Now, did I just deny the doctrine of eternal security (that the blood of Jesus, which saves us, keeps us saved)?
Allow me to elaborate.
If someone has a nominal, lukewarm, or shallow faith, they can fall away (Luke 8:12-13); and if they fall away, they no longer have salvation.
If someone has a heart faith that is unto righteousness (Romans 10:10) and enduring to the end (Matthew 10:22, Hebrews 3:6, Hebrews 3:14), then their faith is unto everlasting life (John 6:47)...life that can never come to an end...otherwise it would have been defined as temporal.
And therefore the exhortation is this:
Phl 2:12, Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling.
which means,
2Pe 1:10, Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:
It should also be clear that if anyone ceases to walk in Christ's goodness, the same will be cut off:
Rom 11:20, Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear:
Rom 11:21, For if God spared not the natural branches, take heed lest he also spare not thee.
Rom 11:22, Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shalt be cut off.