For God so loved the world, that he gave his one and only Son, that whoever believes in him should not perish, but have eternal life.
But have everlasting life ... Such an unspeakable reward contrasts with God's wrath (John 3:36), destruction  (Matthew 7:13,14), eternal fire  (Matthew 18:9), and with judgment or death (John 5:24).  Everlasting life is antithetical to such things, being eternal both in its excellence and in its duration.