[Bob434]

Have you in your heart accepted Jesus Christ as Savior? If so, then you have God’s assurance of your salvation- Assurance is based on God assuring us we are saved IF we accept His son in the manner in which He tells us we must-

“Is your trust in the Christ who died for you and was raised for you? Do you trust in Christ’s death and resurrection on your behalf? If the answer is “yes”, then you have God’s own word and faithfulness that you have eternal life and will spend eternity with Christ.”

https://doctrine.org/assurance-of-salvation

The above link gives a very good rundown on assurance-

As well, The Fruit of hte Spirit is evident in His people- it is evidence that a person is saved- THis is another assurance from God-

[MurphsLaw]

Bob,
When I read:

19 My brethren,
if any one among you wanders from the truth and some one brings him back,
20 let him know that whoever brings back a sinner from the error of his way will save his soul from death and will cover a multitude of sins.

I'm not so sure thst we can't stray from the Truth we have already been given- unto our spiritual death.
Now we can be brought back- repentance- and maybe even fall away again-

But if this can happen, maybe the wages of sin are really death...