Jesus tells us in John 3:15-16 that whoever believes in Jesus Christ will have eternal life, not might have but actually possesses that everlasting life. If a person is promised eternal life and then to have it taken away then it was never eternal to begin with and it makes Jesus out to be a liar and the promises of God to be false. Below we see more promises the believer can count on for eternal life now and in the future. We can be confident in the promises of God.
Jesus and the Apostles below rebuke your false gospel. Belief is the condition to receive eternal life.
John 3:16
16 "For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life.
John 3:36
"He who believes in the Son has eternal life;
John 5:24
"Truly, truly, I say to you, he who hears My word, and believes Him who sent Me, has eternal life, and does not come into judgment, but has passed out of death into life.
John 6:47
"Truly, truly, I say to you, he who believes has eternal life.
John 6:54
54 "He who eats My flesh and drinks My blood has eternal life, and I will raise him up on the last day.
John 20:31
But these are written that you may believe that Jesus is the Messiah, the Son of God, and that by believing you may have life in his name.
1 John 5:13
These things I have written to you who believe in the name of the Son of God, so that you may know that you have eternal life.
hope this helps !!!