Here is a post by Steve Hays which reflects some of my thoughts, but, as usual, he says it better.
18 Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God (Jn 3:18).
36 Whoever believes in the Son has eternal life; whoever does not obey the Son shall not see life, but the wrath of God remains on him (Jn 3:36).
22 Who is the liar but he who denies that Jesus is the Christ? This is the antichrist, he who denies the Father and the Son (1 Jn 2:22).
every spirit that confesses that Jesus Christ has come in the flesh is from God, 3 and every spirit that does not confess Jesus is not from God (1 Jn 4:2-3).
7 For many deceivers have gone out into the world, those who do not confess the coming of Jesus Christ in the flesh (2 Jn 7).
6 This is he who came by water and blood—Jesus Christ; not by the water only but by the water and the blood. And the Spirit is the one who testifies, because the Spirit is the truth (1 Jn 5:6).
the life was made manifest, and we have seen it, and testify to it and proclaim to you the eternal life, which was with the Father and was made manifest to us (1 Jn 1:2).
14 And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth (Jn 1:14).
But when the Helper comes, whom I will send to you from the Father, the Spirit of truth, who proceeds from the Father, he will bear witness about me. 27 And you also will bear witness, because you have been with me from the beginning (Jn 15:26-27).
the Father who sent me bears witness about me. (Jn 8:18).
Jesus answered them, “I told you, and you do not believe. The works that I do in my Father’s name bear witness about me (Jn 10:25).
6 There was a man sent from God, whose name was John. 7 He came as a witness, to bear witness about the light, that all might believe through him…29 The next day he saw Jesus coming toward him, and said, “Behold, the Lamb of God, who takes away the sin of the world! 30 This is he of whom I said, ‘After me comes a man who ranks before me, because he was before me.’ 31 I myself did not know him, but for this purpose I came baptizing with water, that he might be revealed to Israel.” 32 And John bore witness: “I saw the Spirit descend from heaven like a dove, and it remained on him. 33 I myself did not know him, but he who sent me to baptize with water said to me, ‘He on whom you see the Spirit descend and remain, this is he who baptizes with the Holy Spirit.’ 34 And I have seen and have borne witness that this is the Son of God” (Jn 1:6-7,29-34).
30 “I can do nothing on my own. As I hear, I judge, and my judgment is just, because I seek not my own will but the will of him who sent me. 31 If I alone bear witness about myself, my testimony is not true. 32 There is another who bears witness about me, and I know that the testimony that he bears about me is true. 33 You sent to John, and he has borne witness to the truth. 34 Not that the testimony that I receive is from man, but I say these things so that you may be saved. 35 He was a burning and shining lamp, and you were willing to rejoice for a while in his light. 36 But the testimony that I have is greater than that of John. For the works that the Father has given me to accomplish, the very works that I am doing, bear witness about me that the Father has sent me. 37 And the Father who sent me has himself borne witness about me. His voice you have never heard, his form you have never seen, 38 and you do not have his word abiding in you, for you do not believe the one whom he has sent. 39 You search the Scriptures because you think that in them you have eternal life; and it is they that bear witness about me, 40 yet you refuse to come to me that you may have life. 41 I do not receive glory from people. 42 But I know that you do not have the love of God within you. 43 I have come in my Father’s name, and you do not receive me. If another comes in his own name, you will receive him. 44 How can you believe, when you receive glory from one another and do not seek the glory that comes from the only God? 45 Do not think that I will accuse you to the Father. There is one who accuses you: Moses, on whom you have set your hope. 46 For if you believed Moses, you would believe me; for he wrote of me. 47 But if you do not believe his writings, how will you believe my words?” (Jn 5:30-46).
Some argue that the term “world” here [Jn 3:16] simply has neutral connotations—the created human world. But the characteristic use of “the world” (ho kosmos) elsewhere in the narrative is with negative overtones—the world in its alienation from and hostility to its creator’s purposes. It makes better sense in a soteriological context to see the latter notion as in view. God loves that which has become hostile to God. The force is not, then, that the world is so vast that it takes a great deal of love to embrace it, but rather that the world has become so alienated from God that it takes an exceedingly great kind of love to love it at all. A. Lincoln, The Gospel According to St. John(Henrickson 2005), 154.
If here [1 Jn 2:2] it is a reference to the whole planet, consideration of the historical context in which John wrote makes a more likely interpretation to be the universal scope of Christ’s sacrifice in the sense that no one’s race, nationality, or any other trait will keep that person from receiving the full benefit of Christ’s sacrifice if and when they come to faith.
In the ancient world, the gods were parochial and had geographically limited jurisdictions. In the mountains, one sought the favor of the mountain gods; on the sea, of the sea gods. Ancient warfare was waged in the belief that the gods of the opposing nations were fighting as well, and the outcome would be determined by whose god was strongest. Against that kind of pagan mentality, John asserts the efficacy of Jesus Christ’s sacrifice is valid everywhere, for people everywhere, that is “the whole world.”
But “world” in John’s writings is often used to refer not to the planet or all its inhabitants, but to the system of fallen human culture, with its values, morals, and ethics as a whole. Lieu explains it as that which is totally opposed to God and all the belongs to him. It is almost always associated with the side of darkness in the Johannine duality, and people are characterized in John’s writings as being either “of God” or “of the world” (Jn 8:23; 15:19; 176,14,16; 18:36; 1 Jn 2:16; 4:5). Those who have been born of God are taken out of that spiritual sphere, though not out of the geographical place or physical population that is concurrent with it (Jn 13:1; 17:15: see “In Depth: The “world” in John’s Letters” at 2:16).
Rather than teaching universalism, John here instead announces the exclusivity of the Christian gospel. Since Christ’s atonement is efficacious for the “whole world,” there is no other form of atonement available to other peoples, cultures, and religions apart from Jesus Christ. K. Jobes, 1, 2, & 3 John (Zondervan 2014), 80.