Matt 5:20 or enter you won't., page-42

Hello.
"Faith is from personal effort."
Verses where Paul teaches that please.
..
"...Christ's work; not yours."
Correct , your works/personal efforts can not and do not save/justify you.
..
Once you are saved/JUSTIFIED you are SEALED Eph 1:13.
In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,
..
Do you teach that a saved/sealed believer can become unsaved/unsealed ?
If so, where does Paul teach that ?