What is the meaning of just in the prayer sentence:
Lord, we just want to ask for your grace
Does the word in some way minimize the request?
Put another way, what is the effect of using just in a sentence such as the following?
God, we just want to thank you for the gift of Salvation
In addition to the denotation of "I want nothing else", just want often has the implication or connotation that what is wanted is not a big deal, or is not a cause for concern, etc. There can be, indeed, a sort of diminishing involved.
I just wanted to drop by your new cubicle and say hello.
I just wanted to take a minute to go over these numbers.
I just wanted to take a peek at her sleeping. I wasn't going to wake the baby.
That's probably not the meaning in the context of "the gift of Salvation" :-)
But sometimes just want carries the implication of "it is only fitting and proper" or that what is being said is heartfelt, that the speaker is expressing humility or deference. That is where the diminishing comes into the picture.
I just wanted to say thank you for all the help and support you've given us during this difficult time.
Humility is most likely the intended connotation in your sentences, thanking God for the gift of salvation or asking for grace.
If we had to paraphrase it woodenly, imagining God as CEO:
We won't take up any more of your valuable time, God, than is necessary to do one thing, namely, express our gratitude for salvation.
I wouldn't say that it "minimizes" the request; I'd say that it intensifies the focus of the request.
Yes, we can use just to emphasize how small something is. For example, a salesman might say:
I'm just asking for a minute of your time.
but I don't think that's the same as when we are talking about God's mercy in a prayer.
Sometimes, we're not trying to say that something is small. Instead, it's more akin to when someone says:
I just want to thank all those who helped in the rescue efforts
The word "just" serves as an intensifier there. We could even take it out of the sentence without changing its meaning:
I want to thank all those who helped in the rescue efforts
Moreover, it certain isn't meant to diminish the accomplishments of the rescuers – not in the same way the salesman is trying to trivialize the amount of time he was requesting.
As @stangdon says in a comment, it's more about focusing on the moment.
Wordnik offers an interesting meaning, among several others for just:
just (adv.) Used to show humility
I think this is why we see this word used often in prayers and commencement speeches; people are humbled by all they have been given, and they just want to express their heartfelt gratitude.
"I just want you to be happy" implies "The only thing I want is for you to be happy".
One implication is that because this is the only thing I want, I actually want it very much: it's the top of my priority list.
At the same time, it's saying: please don't assume I have other motives. Saying "I just want to thank you" means "I'm not expecting anything in return". (Which may or may not be true, of course.)
The general form of your question is
What is the meaning of 'just' as an adverb?
The OED lists 4 main senses in current use, 2 obsolete senses, 11 phrases, 2 compounds. All of them derive from the adj. 'just' from Latin 'iustus' ("lawful") but, since English had the separate word 'justly' that feels more appropriate for all the "lawfully" and "appropriately" senses, the adv. 'just' came to focus on the sense meaning "exactly" or, concerning verbs in the past tense, "almost exactly before".
From there, you get
5. Limiting the extent or degree denoted by an expression: only as much as, not much more or less than; barely, by a little, by a slight margin.
...
6.... a. No less than; absolutely; actually, positively, really. In weakened sense: neither more nor less than, no other than; simply, merely.
In other words, it became a synonym of "merely" or "only [the thing I'm about to describe]".
Therefore, in your prayers
Lord, we just want to ask for your grace...
G-d, we just want to thank you for the gift of Salvation...
the effect of the 'just' is to underline that you want the Almighty to believe—rightly or wrongly—that no ulterior motive prompts your action. The only thing you wish to do is request grace, not defend yourself or pretend to blamelessness or offer mitigating excuses for your many sins against His Law. The only thing you wish to do is thank Him, not request a favor or ingratiate yourself or put on a pious show for the community.
It is a rather self-defeating turn of phrase. It instantly brings to mind Danish noblewomen "protesting too much" or liars throwing in a "you gotta believe me" or "when have I ever lied to you" that instantly reminds you of several instances. Someone who is honestly just asking would, in fact, just ask. One might easily contrast it with the direct—even blunt—phrasing of, e.g., the Lord's Prayer offered by the guy who was so pissed at the Pharisees' showy piety.
On the other hand, as a Christian prayer, it could easily be taken as instructive or aspirational. The dogma goes that—with very few and explicitly listed exceptions—mankind is born, lives, and dies in sin and their forgiving Father knows the deceit and self-interest that prompt most prayers. A truly pious person wouldn't pray this way, but a self-aware sinner might. Similarly, a church might enjoin it, intending that the laity should be reminded that Christians should try to overcome the many limitations to their kindness and love, beginning with their relationship to the Almighty.
Largely it is used where people are praying spontaneously and as such, it's an cliche which doesn't mean much, but allows you to start talking without quite having finished thinking - it's better to start with 'Lord, I just ...' rather than 'erm,....'
"Just" in this case is a synonym for "only" - you'll find that simply replacing "just" with "only" will illustrate that there is no difference in meaning, though there is a difference in connotation in that it minimizes the issue.
God, we "only" want to thank you for the gift of Salvation (and nothing else).
On a side note, I frequently call out small children on the idea of using the word "just" when they get caught doing something they shouldn't be, and then I hear their response: "I was just...(doing whatever)" (as if it wasn't a big deal). I tell them that they aren't allowed to use "just" to (ahem) justify their bad behavior, and then they realize it was wrong.
