John 6:39-40, "This is the will of Him who sent Me, that of all that He has given Me I lose nothing, but raise it up on the last day. For this is the will of My Father, that everyone who beholds the Son and believes in Him will have eternal life, and I Myself will raise him up on the last day."
And, if you don't persevere, then, Calvinists will say you never were really His.
Your sense of OSAS does not bind God.