This is why I think that their needs to be a distinction between the initial and the ongoing.
When it comes to faith, we don't know where the goal post is. Some people are given more mercy than others. An example of this is the thief on the cross. He didn't have the time to verb faith his way into salvation. He was stuck on a cross about to die. The repentance part was enough for Jesus to tell him that he would be
with him in paradise. So you can't fit faith neatly into boxes about how much or how little as well as circumstances may differ too. Verb faith is for the people who are living and
can actively put it into practice. But even then, there isn't a clearly defined goal post. God knows what faith is saving faith vs just merely belief. That distinction matters.
Okay, getting into Romans 1:16-17
For I am not ashamed of the gospel of Christ, for it is the power of God to salvation for everyone who believes (pisteuō), for the Jew first and also for the Greek. For in it the righteousness of God is revealed from faith (pistis) to faith (pistis); as it is written, “The just shall live by faith (pistis).”
Paul doesn't need to use the verb form of faith in verse 17 because he's spelling it out with "the just shall
live by faith". But it is backed up with the verb form when it says "believes". So when you say you think it's initial + ongoing, actually its just ongoing and the verses don't have any indication it's talking about initial. Because "everyone who believes" already indicates already ongoing faith in action due to the verb form.
Now let's take Romans 3:3 and Romans 3:22
Romans 3:3
For what if some did not believe (apisteō-v)? Will their unbelief (apistia-n) make the faithfulness [of God (theos)] without effect?
So firstly, it would read, "what if some did not put faith into action?" Which makes the rest of the verse make more sense right? Essentially Paul is saying this: "So if someone doesn't put faith into action, does their unfaithfulness cancel out God's faithfulness?"
And it's translate "of God" to make more sense in english but its literally just "theos" meaning God. The "of" part is added due to grammar and how english is structured.
Romans 3:22
even the righteousness of God, through faith (pistis) in Jesus Christ, to all and on all who believe (pisteuō). For there is no difference;
So through belief in Jesus, to all who verb faith believe. - Essentially. Which also doesn't indicate initial faith.
Now Galatians 2:20
I have been crucified with Christ; it is no longer I who live, but Christ lives in me; and the
life which I now live in the flesh I live by faith (pistis) in/
of (ὁ) the Son of God, who loved me and gave Himself for me.
He doesn't need to use the verb form here because he already established he lives it out "I now live" so it's fine he used the noun version. Now, when it comes to of/in its the definite article ὁ which technically makes the verse supposed to read "of" instead of in. Which makes more sense because Paul is pushing Jesus to the forefront of his life by saying Christ is the one doing the work. So it makes sense it would mean "of" the Son of God because it's Christs work that is doing it and not center focus of YOU doing something IN Christ. Does that make sense?
But in each of these examples there is nothing here that denotes a start point of faith. It is always ongoing, continual, don't cease and active. So I wouldn't frame this as "there isn't the holy spirit at the start of faith" because scripture honestly, doesn't back this up. God could give you the holy spirit right at the beginning because the point of the holy spirit is to guide us, correct us and help us walk righteously and it's always at the start that we need the most help. Now, where the goal post is for solid salvation (because you can walk away at any time), only God knows with each persons individual walk.
There was a lot you mentioned and I hope I covered it all. If I didn't, just let me know.