To answer this question, we really first of all need to go through the terms you are using and define them.
Also, we must go through the verses you are quoting. Then we might come to a conclusion.
So as you say, doubt and waswas might not be the same thing, they might be related, but that again depends of your definition of the word waswas.
What does waswas mean?
- Whispering. Which mostly is understood to come from Satan in a religous point of view. Please note that there are discussions about what type of "whisperings" really are coming from Satan and which aren't.
- Obsessional thoughts, OCD, see: http://www.ocduk.org/types-ocd
Now, if one has OCD, one should visit a doctor which specialize in this area. Because thats more counted as a psychological disorder. God is Just and doesn't punish someone for something she/he cannot control. See:
Allah does not charge a soul except [with that within] its capacity. It will have [the consequence of] what [good] it has gained, and it will bear [the consequence of] what [evil] it has earned. "Our Lord, do not impose blame upon us if we have forgotten or erred. Our Lord, and lay not upon us a burden like that which You laid upon those before us. Our Lord, and burden us not with that which we have no ability to bear. And pardon us; and forgive us; and have mercy upon us. You are our protector, so give us victory over the disbeliev
Let a man of wealth spend from his wealth, and he whose provision is restricted - let him spend from what Allah has given him. Allah does not charge a soul except [according to] what He has given it. Allah will bring about, after hardship, ease.
The doubts could of course be treated as either one of the types of waswas. It could also be related to other things, one could not know for sure. If it's OCD, it might be easier for a specialist to draw the conclusion that it is the source. But doubts could also come from other sources, it musn't be waswas. But one might call all doubts from satan, following the philosophy: "everything that brings you away from Islam, is from Satan".
The verses about doubt
Analyzing the first verse, Surat AL-Hujurat, verse 15
The message of this verse is to say that "the TRUE believers are...". Reading the verse before it (i.e verse 14):
The desert Arabs say, "We believe." Say, "Ye have no faith; but ye (only) say, 'We have submitted our wills to Allah,' For not yet has Faith entered your hearts. But if ye obey Allah and His Messenger, He will not belittle aught of your deeds: for Allah is Oft-Forgiving, Most Merciful."
Meaning that they were Muslims. The verse later one explains the conditions for them, about TRUE belief:
The believers are only those who believe in Allah and His Messenger
then they doubt not and struggle hard with their wealth and their
lives in the way of Allah; they are the truthful ones.
The tafsir here might also be interesting.
There are many hadiths related to TRUE belief. For instance the hadith:
“You will never believe until you love each other. Shall I tell you what will make you love each other?” They said, “Of course, O Messenger of Allah.” He said, “Spread peace between yourselves. By the one in whose hand is my soul, you will not enter Paradise until you are merciful.” They said, “O Messenger of Allah, all of us are merciful.” He said, “Verily, it is not mercy between yourselves, but rather it is mercy in general; it is mercy in general.”
The message of the hadith isn't not talking about belief itself, it is talking about the highest LEVEL of belief. You can believe and be a bad person, you can believe and hate everyone and be unjust - but you will never be a TRUE believer.
Analyzing the second verse, Surat Qaf 24-25:
[ Allah will say], "Throw into Hell every obstinate disbeliever,
"Who forbade what was good, transgressed all bounds, cast doubts and
Reading the next verse (26):
"Who set up another god beside Allah: Throw him into a severe
The verse doesn't entirely mean the person who doubts, it might also mean the person who makes people doubt. Even if it means a person who doubts, it is still baked in to many conditions:
- A person who set up another god besides Allah. (Moshrik)
- A person who forbids good.
- Exceeds all the limits (in a negative way)
- Makes other people doubt (calling the message a lie), OR it could also be interpreted as he doubts about the message (after beeing clear to him)
You might also know that there are different of opinions about WHO is a kafir. You can read about that in this forum.
In my perspective, the verses you quoted has nothing to do with your situation. The context is not the same.
You might have heard this from me before, but I truly believe your problems are based on you drawing conclusions too fast. You do this by being certain about your interpretation of certain hadiths/verses are absolutely true, which then make you draw conclusion that will be false (if the interpretation is false).
You should take a step back, if you really are concerned you should study for real, not reading some verses and hadith in the net. This can really be an "iman" killer, if you aren't experienced, just like one who cannot swim will drown (and die) if one jumps into the deep ocean.
I recommend you to study Arabic, Logic, Rhetoric, Argumentation analysis, Usul Al Fiqh. Keep away from the deep ocean until you do know how to swim.