For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved. He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God. John 3:16-18.
Here we have the heart of the gospel, the starting place for thinking "Christianly." The "for" of verse 16 reflects us back to verses 14 and 15 and the importance of having faith as we look upon Jesus on the cross.
But verse 16 carries our understanding a giant step forward. Jesus didn't get on the cross all be Himself. No, He had been sent by the Father who so loved the world that He gave His one and only Son (the real meaning of "begotten") to rescue the inhabitants of Planet Earth.
Here we find an important truth about God the Father: He took, and always takes, the initiative in our salvation. He is not some standoffish deity who must be pacified or who is stern and angry with sinful humans. To the contrary, He loved sinners so much that He took the lead in providing them with the solution to the problem of sin and death. It is time to move beyond the contrast between a condemning God and the sweet, loving, and gracious Jesus who needs to change the Father's attitude. John 3:16 tells us that They are in this together. It all started with the Father. In His love He sent the Son not to smash and punish sinners, but to save them.
John 3:16 tells us something else about God. Namely, that He "loved the world." All of it, not just some nation or social group, not merely a part who have been selected out of the masses of spiritually destitute for heavenly bliss, but all of it. He "loved [and loves] the world." That includes you and me.
And that thought leads to what John 3:16 teaches about us. The key ideas are two. One is that without God's rescue plan we will perish. The second is that we must respond to God's offer. We are born needing salvation. Thus "whosoever believeth" is the truth set forth by Jesus.
The good news is that the gracious God who loves the world also supplies each of us with the power to believe in that Jesus who was uplifted on the cross for us. Today is the day to take God's gift of belief and let Jesus into our hearts.