In the parable of the sower, only the 4th soil "good ground" produced a crop (fruit) of various sizes, proving to be saving belief. Unlike the other soils. Faith without works is dead. Belief that saves involves faith, trust, reliance and not simply mental assent belief. In regard to demons, their trust and reliance are in Satan as demonstrated by their rebellion in heaven and continuous evil works. Salvation is not available to them. They already dug their grave and now they will lie in it.
I think you gotta be careful what you put as things a believer WILL be seen doing.
Salvation is purely knowing you are a sinner, deserving hell, and believing Jesus is God, lived sinless and died and rose again. By believing in Him you have eternal life.
So.. this may not be obvious to a person who cannot see their heart.
A person who has believed may not have a faithful walk with God..particular if they are a new believer still dealing with recently being in lost ways of living. Even a seasoned believer has weaknesses in their faith.
Not saying you are, but 'back loading' works into Salvation is something you gotta be careful not to do.
'Faith without works is dead' doesn't mean if works aren't seen..there was no belief. The context isn't about salvation but what a person who already is converted.. can do with their faith to profit others.
Because the Holy Spirit indwells believer.. then there will be fruit from this indwelling in the believers life..and discipline for the believer when they trip up.. but the fruit isn't the test..but whether they believed on the Lord Jesus Christ.