I guess that I will have to disagree with the idea that the 'whole world' means the Elect only.
You will have to prove that John was addressing the whole world when he wrote his letter. Of course, the context of the letter helps.
1 John 1:3-10
...that which we have seen and heard we proclaim also to you, so that you too may have fellowship with us; and indeed our fellowship is with the Father and with his Son Jesus Christ. And we are writing these things so that our joy may be complete. This is the message we have heard from him and proclaim to you, that God is light, and in him is no darkness at all. If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth. But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin. If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. If we say we have not sinned, we make him a liar, and his word is not in us.
1 John 2:7
Beloved,
I am writing you no new commandment, but an old commandment that you had from the beginning. The old commandment is the word that you have heard.
1 John 2:7,12-14
Beloved,
I am writing you no new commandment, but an old commandment that you had from the beginning. The old commandment is the word that you have heard. I am writing to you,
little children,
because your sins are forgiven for his name’s sake. I am writing to you,
fathers,
because you know him who is from the beginning. I am writing to you,
young men,
because you have overcome the evil one. I write to you,
children,
because you know the Father. I write to you,
fathers,
because you know him who is from the beginning. I write to you,
young men,
because you are strong, and the word of God abides in you, and you have overcome the evil one.
Now, please provide text in his letter that says John is writing to the entire world, including those outside of the Christian faith. I suggest that you will have to torture one verse to make your claim.
You are free to disagree. My point is that I believe I have the better argument from scripture.