OSAS came from the theory of irresistible grace taught by the Calvinists!
If you believe man cannot lose his salvation you are a part of that theory!
Don't know anything about what a Calvinists believes or care.
I have no clue, If "they" coined the Phrase...;
Once Saved Always Saved
What Scripture teaches;
Is receiving Salvation of ones Soul, is a Gift FOR a "CONVERTED" man.
The fact is ANYONE can believe, and NOT BE "CONVERTED", and fall from faith.
Men do not Receiving Gods Gift of Salvation, without Conversion....plain and simple.
Men do not have the POWER to Convert a man.
Men do not have the POWER to strip AWAY a mans Salvation.
Scripture is full of WARNINGS and CAUTIONING believing men, to be steadfast in their faith....OFCOURSE....that will lead such men to their CONVERSON and receiving of Gods OFFERED Gift of Salvation.
If you do not believe there ARE MEN who BELIEVE and ARE NOT CONVERTED...
IF you attend a Church, see the same faces week after week, even year after year, and all of a sudden one of those familiar faces, goes to an altar call....to CONFESS his Belief and Receive his conversion, and receive Gods Offered Gifts, (one being Salvation of his soul)....
Don't you realize that man was A BELIEVER, but NOT Converted? (Not Saved?).
If he had Stopped Believing, he did not LOSE his Salvation, BY (RECEIVING IT, and
THEN having his Salvation stripped away.
He Lost his Salvation, by NEVER CLAIMING IT, by CONFESSION.