Great Bible studies into the topic of Once Saved Always Saved.

https://bibleprophecytalk.com/i-was-wrong-about-once-saved-always-saved-and-my-backsliding-testimony/
https://bibleprophecytalk.com/more-thoughts-on-once-saved-always-saved/

https://www.instagram.com/p/Cu2wZikMqNr/ (one minute)
OSAS teachers tell us that: 
no virgin's lamp can go out
no harvest can be choked with thorns
no branch can ever be cut off
no unfruitful tree cut down and thrown into the fire
no name blotted out of the book of life
they insist:
that no salt can ever lose its savor
that no one can ever receive the grace of God in vain
that no one can bury his talents
that no one look back after putting his hand to the plow
they say that nobody can grieve the Spirit til he is quenched and strives no more 
or deny the Lord that bought them
they say that no Christians will be told 
"Depart I never knew you."
and that nobody will ever get so lukewarm that
Jesus will spit them out of his mouth
they will argue that if anyone ever get lost
it just proves he never was found
that if anyone falls, he never stood
that if anyone if ever thrown away, he was never in
that if anyone ever withers, he was never green
that if anyone ever falls away into darkness, he was never in the light
that if you ever get entangled again into the pollutions of this world,
that it just shows you never escaped
that if you make a shipwreck of your faith
there was never a ship of faith in the first place
In short they say, "If you get it you can't lose it."
and "If you lose it, you never had it."
May God save us from a doctrine that must be defended in this way.

(I didn't get every word right in my transcription of his little video.)