Are you saying that on the cross Jesus only paid for some people's sins and not all people's sins?
Jesus laid down His life and paid for sins, but only those of His sheep - the elect's- not everyone's.
John 10
14 I am the good shepherd, and
know my [sheep], and am known of mine.
15 As the Father knoweth me, even so know I the Father: and
I lay down my life for the sheep
[Jhn 10:27-29 KJV]
27
My sheep hear my voice, and I know them, and they follow me:
28
And I give unto them eternal life; and they shall never perish, neither shall any [man] pluck them out of my hand.
29 My Father, which gave [them] me, is greater than all; and no [man] is able to pluck [them] out of my Father's hand.
The same with believing - only His sheep will truly believe
[Jhn 10:26 KJV]
26 But ye believe not, because ye are not of my sheep, as I said unto you.
They only enter in by Him.
[Jhn 10:3, 9 KJV]
3 To him the porter openeth;
and the sheep hear his voice: and
he calleth his own sheep by name, and leadeth them out. ...
9 I am the door:
by me if any man enter in,
he shall be saved, and shall go in and out, and find pasture.