This website tries to show that these three ideas are true:
A Christian cannot lose their eternal salvation: God knows who is truly willing to go to Heaven and if they will have to change to go to Heaven. Therefore, God knows when someone is willing to change to go to Heaven.
Whoever has eternal life really wants to live eternally with God instead of being lost to sin (John 3:16; 17:3). That means, they hope that they don't ever come across something and follow it back onto the path to Hell.
God uses this willingness and honest desire for Heaven to provide His children with enough good reason to stay with Him.
A person is saved by faith alone, and do not have to think about how they live to know if they have faith: Someone can know they have true faith in Jesus just because they have faith. In other words, a person doesn't need to see actions to know Who they believe Jesus is and what they are believing in Him for.