WONDROUS= Amazing, out of the ordinary.

A SET OF PRINTS= A couple of footprints, the marks left by a person walking.

A SET OF PRINTS ON THE SAND WAS SEEN= The order of the sentence is not the "correct" one. We call it hyperbaton, and it is ok in poetry (but not in normal language) because it creates a strange effect and sounds beautiful. The normal order for this sentence would be: A set of prints was seen on the sand. You can find more hyperbatons on this poem.

PRECIOUS= /preʃəs/ Very valuable or loved.

LORD= God.

YET= But; nevertheless.

SHORE= Beach (the strip of coast where the sea meets the land)

A STRANGER= A stranger is an unknown person, but here it is the comparative form of the adjective STRANGE, so "a stranger print appeared" means: a mark which was "more strange" than the others appeared on the sand.

WHAT HAVE WE HERE?= A colloquial way of asking "what's this?", used to show surprise.

LARGE= /lɑ:*dʒ/ Big.

NEAT= Nice, beautiful, well-made. But in this context it means "well defined, easy to see".

IT'S JUST TOO BIG FOR FEET= It can't be a foot-print because feet are not so big.

SOMBRE= (AmE spelling: somber) Melancholic, sad, worried.

IN SOMBRE TONES= If you speak in sombre tones, you speak in a tone of voice which is melancholic, sad or/and worried.

I CHALLENGED YOU= If you challenge someone (to do something), It is a difficult thing to do, but you press them to do it as a way to prove their value or capacity.

SEEK= Look for.

MY FACE= The face of God is the knowledge of God, so if you see God's face, you understand the truth, you finally understand what life really is and what you have to do about it. Basically, when you find God's face, you know how to live your life with love.

TAKE UP YOUR CROSS= This is, obviously, a Christian image. Jesus died on the cross to save us, but before dying on the cross he had to carry the cross Himself and suffer all the way up to the mount where he was crucified. So "to carry your cross" means to be strong and brave through a difficult situation and not to give up. If you TAKE UP YOUR CROSS, you decide to assume responsabilities when life becomes difficult, instead of running away and simply getting depressed or entertained while you do nothing about it.

IN GRACE= With the blessing of God, with His protection and approval.

YOU WOULD NOT GROW= You didn't want to grow, you refused to grow. In this sentence, the verb WOULD is not the auxiliary verb to form the conditional tense, but the past tense of the verb WILL, which means (not future but) "want".
- Will you come to my party? = Do you want to come?
1- I went to her house many times but she won't open the door = she doesn't want to open the door; she refuses to open the door.
2- I went to her house many times but she wouldn't open the door = she didn't want to open the door; she refused to open the door.
The difference between sentence 1 and sentence 2 is that sentence 1 is still true, so the situation is present and she still doesn't want to open the door. In sentence 2 we are talking about a past situation, she refused to open the door in the past, we are not talking about what happens now.

YOU WOULD NOT STAND AGAINST THE FLOW= You didn't want to stop doing the same things as everybody else. THE FLOW is the general behaviour, what everybody thinks or/and does. TO STAND (UP) AGAINST SOMETHING means to be brave and oppose something although people may criticize or attack you for doing so.

NECK= The part where your head and body join.

STIFF= Rigid. The opposite of flexible.

YOUR NECK WAS STIFF= You didn't want to change the direction of your life. If you have a stiff neck, you can't move it because it hurts a lot (maybe because you slept in a bad position), but here it means that you keep your neck (and your head) rigid, always in the same position, because you are walking always in the same direction, without changing your way. So metaphorically, it says that your life is wrong but you don't want to change it.

SHUT= (shut-shut-shut) Closed.

YOUR EARS WERE SHUT= You didn't want to listen. If you close your eyes, you can't see, if you close your ears, you can't hear. Of course you can't close your ears, but it is a metaphor, it means that you don't hear because you decided not to.

DROPPED= If you drop something, you throw it down or it falls from your hands. In this case God dropped him on purpose as a kind of a shock (because He wanted him to wake up and start doing something with his life)

BUTT= Button, the part of your body where you sit.

TAKE A STAND= If you take a stand, you make a decision or take an opinion and you are ready to defend it.

BUTT-PRINT= This word is modelled after "footprint", so it is the mark that a butt leaves on the ground when you sit on it (or fall down on it).