When God confronted Adam and Eve after their sin in the Garden of Eden, see Genesis 3:1-24, He pronounced a series of curses and punishments; within this God made reference to the coming Christ who was to take away the sin of the world.
“The ELDER, To the elect lady and her children, whom I love in truth, and not only I, but also all those who have known the truth, because of the truth which abides in us and will be with us forever…” 2 John 1:1-2.
“These things I have written to you who believe in the name of the Son of God, that you may know that you have eternal life, and that you may continue to believe in the name of the Son of God.” 1 John 5:13.
“Now this is the confidence that we have in Him, that if we ask anything according to His will, He hears us. And if we know that He hears us, whatever we ask, we know that we have the petitions that we have asked of Him.” 1 John 5:14-15.
“This is He who came by water and blood – Jesus Christ; not only by water, but by water and blood. And it is the Spirit who bears witness, because the Spirit is truth.” 1 John 5:6.