YOU need to know that you belong to Him.
I do.
His works in me may produce works of righteousness but the newness of mind paired with trust in His promises is enough to remove any doubt.
If you choose to look to your works for "evidence" or comfort that's on you. I will trust in Him.
If you have those things, and are continuing in those things, then you know that you belong to Him.
If you don't have them, or are not continuing in them, you may not belong to Him at all.
You need to know for sure before Jesus returns.
You may never know you are saved for sure if you take false comfort in some misguided 'I don't have to do anything' doctrine of assurance.
Not having works of righteousness is actually where fear and lack of assurance comes from.
Diligence in works gives the believer full assurance of salvation right to the very end of life.
No works leaves the 'believer' wondering in lack of assurance if they really have Christ in them in salvation.
I don't agree with the way you word this.
In this forum alone, I have fallen short of doing exactly what I should do. Even overlooking an offense can be a work of righteousness. (and the opposite can be the opposite especially if done in a far less than patient way)
Also I have done as I should have. Even if it was the hard thing to do.
God has used me in many ways and moved me to help others and share what He has provided. (time energy or resources)
My assurance doesn't come from any of this nor suggest I was never saved at all.
This is me being less than perfect plenty of room for growth and constant need of God for not only forgiveness but also leadership in order to be useful to Him I am GRATEFUL to.
Torment doesn't belong next to my assurance and tied to the number or frequency of "works".
Before being born again it is very easy to try to justify your errors. Afterwards you know better and even if your message is correct you may feel convicted about your delivery. Even if you share what God provides you may feel convicted by talking about it after as if maybe it sounded like a boast.
After being born again we know our Father sees us and we trust He is always right.
A sappling may still do things that aren't works of righteousness, and also not have anything big to point at..... but they shouldn't look to what they have done for assurance.
They should look to Gods promises, trust in them and then ask Him who they trust for the newness He promises.