The letter of First John makes several direct references to the universality of Jesus’ atonement.
He is the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world. (1 John 2:2 NIV – bold mine)
And we have seen and testify that the Father has sent his Son to be the Savior of the world. -1 John 4:14
In these passages John states that Jesus atoned for the sins of the whole world, and came to be Savior of the the world. The Greek word for world is kosmos. The English word “cosmos” is derived from this word.
Calvinists sometimes assert that kosmos in the context of John’s letter is limited to “to elect individuals from all nations”. The problem is that this interpretation is not applied consistently. And it does not make sense in context of how John uses the word elsewhere in the letter.