Father, Have I Sinned?

[crimsonqueen]

Hello crimsonqueen.  The biggest problem I have with this is your fallacious assumption that dactylic pentameter -- or indeed any measure of dactyls -- is stilted.  Quite the contrary -- any regular meter will have a consistent, unbroken and logical beat to it.  Additionally, any lines of poetry that use a variety of meters consistently will also sound consistent (to continue with dactyls, consider the elegiac couplets of Ovid and other classical poets). The stilted feel to this poem is because you've mixed your meters inconsistently.  I realise that scansion can be a little subjective and is not an exact science, but I fear that the meter you have in your head is not translating to the page very well.  This can easily be fixed by paying specific attention to the important syllables in a line, the ones you want stressed so they stand out, and working from there -- once the meter is fixed solidly in your head.  Also, it's worth noting that the classic dactyls used by the Greeks and Romans do not work especially well in English due to the tonal differences in the language, so it's best to work on a DUM diddy basis.  Dactyls are a good choice for the gravity of this subject matter, very sombre and powerful when used correctly.

Here, upon a stranded altar, where long days of youth are spent -- this line scans as trochaic to me: HERE u/PON a/ STRANDed/ALtar/WHERE long/DAYS of/ YOUTH are/ SPENT
At first, a hair tousle, that proceeds a firm and impish grip -- this line doesn't scan as regular at all, but definitely not dactylic.  I get: at FIRST/a HAIR/ TOUSle/ THAT PRO ceeds/ a FIRM/ and IMP/ish GRIP, so one dactyl the lot unless you break it up as amphibractic and even then it's not consistent.  Also, it should probably be "precedes".  
The pious servant demands that the sinner, of ten, repent -- and this line: the PIous/ SERVant de/MANDS that the/SINNER of ten/rePENT -- so this one's closest to dactylic pentameter but still not quite right.

Lift up my heavy head, and press the cup to my waiting lip 
We were saved by the blood, and kept by water; seal me in this
For heaven's sake, alone, my hushed mouth will take clandestine sip -- I'll abandon scansion at this point and stick to mild critique, as you have requested.  In this stanza, you do not need "up" after lift -- if it's a choice for meter, it's best to make another choice as it stands out as a filler and meter should not be the driving force in the poem.  You do need an article before "clandestine" purely because of the nature of the rest of your language -- leaving out "a" here draws attention to it as grammatically inconsistent.

How could salvation be odious? I'm sickened by its kiss -- I think the question weakens the concept somewhat.  A statement would have greater power. 
Still, even in the warmth of bed, or mother's breast, or prayer
I'll keep my covenant, and never claim Father is amiss -- amiss is an odd choice.  It's not incorrect, per se, but it more often refers to an action than a person, so the usage here does stand out. It's your choice, however.  

This is very helpful! This was exactly what I was looking for..this format is much trickier to work with than, say, iambs.