You may fall from grace if you are a counterfeit Christian, but if you are a true believer you will never fall from salvation.
Falling from Grace is not the idea of falling from Salvation.
Salvation has an end result that happens as soon as you receive Salvation.. And this end result is that you are BORN.. AGAIN.
So, that never ends, as you cant end a Spiritual Birth.
However, the way you understand Theology.......regarding your Salvation, can become confused and subverted by people who teach wrong theology, who are become ministers of the Devil.
The NT says they are "ministers of righteousness".. yet, they are teaching it according to SELF Righteousness.
This is defined in Heb 13:9 as "doctrines of Devils".
The aim of a Doctrine of Devils is to ruin your understanding of God's Grace, so that you no longer have the Revelation.
And once that happens, then you are deceived, or as Paul defines it....>>"who has BEWITCHED you, so that you no longer obey the Truth".
So what stops this from happening?
Heb 13:9 explains that you must "establish your heart wtih GRACE"...
And that means you have to understand that Jesus not only saved you, but keeps you saved.
See the "keeps you saved" part ??????
This is the part that becomes "broken faith", in a person who is trying to stay saved.
They no longer believe that Jesus keeps them saved., and at that moment, they become "fallen from Grace".