I'm glad the Bible isn't just 1 John 2:2

2 He is the propitiation for our sins, and not for ours only but also for the sins of the whole world. 1 John 2:2

I am glad the Bible consists of more than just 1 John 2:2.  Of course, it wouldn't be called 1 John 2:2 if it were the only verse in the Bible, but that's not the point.  The point is, this single verse has at least three different interpretations argued by Arminians, Calvinists, and Universalists.  Let me show you what they are:

1. The Universalists say this verse shows Christ's atonement covers the sins of every individual in the whole world who has ever lived without condition.  This is because He (meaning, Christ) is the propitiation (meaning He is actively removing God's wrath) for our sins as well as the sins of the whole world (meaning, everyone everywhere who's ever lived).  They understand this to mean if Christ has actively removed the wrath of God from every individual who has ever lived then we're all saved and nobody is going to hell.
2. Like the Universalists, the Arminians say this verse shows Christ's atonement covers the sins of every individual in the whole world who has ever lived BUT due to other verses in the Bible that say there will be people who go to hell there must be an unstated assumption in the verse.  The unstated assumption is "if we have faith".  In other words, his atonement was intended for everyone but is only effective for those who have faith.  Some Arminians would even say Christ's sacrifice literally removed God's wrath from everyone in history for every sin except one: the sin of not accepting Christ's atonement.
3. The Calvinists say the phrase "He is the propitiation" means Christ already removed God's wrath for sins.  The question is "for whom?"  They interpret the intended audience of this verse (as referenced by the words "our" and "ours") to be Christians in the geographic locale where the letter was sent and, due to other verses in the Bible (John 11:52, for instance), "the whole world" to refer to Christians throughout the world.  In other words, Christ's sacrifice was intended to be the propitiation for the sins of the Christian elect, and only the elect, throughout the world.  His sacrifice was never intended to remove God's wrath from every person everywhere throughout history.