You are referring to 1 John 2:2?
1 John 2:2 (YLT)
and he -- he is a propitiation for our sins, and not for ours only, but also for the whole world,
Now, to the novice reader, this appears to mean that Christ took everybody's sins to the cross, and atoned for everyone who ever lived. Even those who died in the mid-centuries, those who never heard the name of Jesus, let alone knew about Him. These who died before missionairies could get to them. It appears that He atoned for them, too.
"NOT SO FAST MY FRIEND", to borrow that line from Lee Corso. Let's take a look at the word 'propiatiation'. I am no Greek scholar, so all I have to go by is Strong's, and I know how some feel about using it.
hilasmos G2434
I.
an appeasing, propitiating
II.
the means of appeasing, a propitiation
IOW, God's wrath is appeased, is satisified, by Christ's propitiating for the lost. So, if Chris did, in fact, propitiate everybody's sins, appeased God's wrath for all sinners, paid their sin debt in full, then none will die and be eternally lost. Their debt is paid, there is no wrath for God to pour out, beacuse God was completely satisified with the work His Son did. That's why a universal atonement leads smack into universalism....