“God so loved the world, that He gave His only begotten Son
That whosoever believeth in Him should not perish, but have everlasting life.”
The loving and giving are God’s side; the believing and having are your side.
Many people are trying to change sides with God - trying to do the loving and giving, and wanting Him to do the believing and having. That is, they are trying to love God and trying to serve Him. Then they hope He will believe in their earnestness and accept their good works and give them eternal life on account of it all.
No, no, NO! That is all wrong. God has loved you and given His Son for you: That is His part. Now do you really believe in Him with your heart? If so, then God says you shall not perish and that you have -have now, here in this world - everlasting life.