When we take a look at John 3:16-17 in the Greek, we see something really unique:
Οὕτως γὰρ ἠγάπησεν ὁ Θεὸς τὸν κόσμον, ὥστε τὸν Υἱὸν τὸν μονογενῆ ἔδωκεν, ἵνα πᾶς ὁ πιστεύων εἰς αὐτὸν μὴ ἀπόληται ἀλλ’ ἔχῃ ζωὴν αἰώνιον.
Houtos gar egapesen ho Theos ton kosmon, hoste ton Huion ton monogene edoken, hina pas ho pisteuon eis auton me apoletai all eche zoen aionion.
The section of "πᾶς ὁ πιστεύων" is very interesting. Most Bibles translate this as, "that whosoever believes," but the word "whosoever" is not actually there. This phrase, "πᾶς ὁ πιστεύων," is used in John 3:15, John 12:46, Acts 13:39, Romans 10:11, and 1 John 5:1. The word "πᾶς" means "all," "every," "the whole," or "every kind of," and modifies "ὁ πιστεύων." Thus, "πᾶς ὁ πιστεύων" more accurately means "all the believing," as in "For God so loved the world, that He gave His only begotten Son, that all the believing in Him shall not perish, but have eternal life." This puts a damper on Calvinist theology. Calvinists twist this to mean something other than precisely what it actually means: "every believing person who abides in Him," as evidenced from numerous other passages. Calvinists, such as James White, suffer from cognitive dissonance. Of course "all the believing in Him" shall not perish. This is not saying anything different than translating it "whosoever believes in Him," except one makes it about belief and the other implies abiding (e.g., "Every branch in Me...").