V 1.

God, the Lord God, has spoken
and summoned the world from the rising to the setting sun.

NLT:  The mighty God, the Lord, has spoken;
he has summoned all humanity from east to west!

The use of repetitive names for God emphasises the power of God. (NIV: the Mighty One, God, the Lord)

Here is a picture of a mighty Lord God in charge, who can summon every human being in the world to be judged.  He has both the right to do so, and the power to give the order and it must happen.

V 2.

God shines out from Zion, perfect in beauty.
NLT:  From mount Zion, the perfection of beauty,
God shines in glorious radiance.

Not only is God powerful, but his beauty is breath-taking - perfect, radiant.
Zion is the name of the hill on which Jerusalem stood and is a reference to the Temple of God or the House of God.  Here is God, enthroned on high, shining and beautiful - an awe-inspiring picture.
(Reminds me of the vision of God enthroned,  in Isaiah 6)

V 3.

Our God is coming and will not keep silence:
consuming fire runs before him
and wreathes him closely round (or: and rages around him)

NLT:  Our God approaches with the noise of thunder.
Fire devours everything in his way,
and a great storm rages around him

Another picture of a powerful God and a God of great energy.  Fire is a symbol of God's power.  A consuming or devouring fire gives an image which reflects God's judgement and justice as being destructive of injustice and cleansing. 

In the Australian bush, when a bush-fire rages through, it clears off all the messy undergrowth and rubbish and clears the way for new growth.  Some plants need the fire to allow their seeds to germinate and produce new life.

NEB: will not keep silence - When God speaks, there is no doubt about who it is who's speaking!  Whe he judges, we know whose judgement it is!

New Bible Commentary, p518.  NIV: not silent - Judgement will not be by an unexplained act where people might or might not recognise it as the work of God.  All will be openly stated.

V 4.

He summons heaven on high and earth
to the judgement of his people:

God calls everything in heaven and on earth to witness to his judgement - as a jury (The Message).  His judgement is never done in secret (see Commentary comment above).  God is never devious; with him everything is up-front.  And he likes us to be up front with him too!

(Question:  I wonder if the root of the word devious is the same as the root of the word devil?)

V 5.
'Gather to me my loyal servants,
all who by sacrifice have made a covenant with me.'

Loyal servants = NIV : consecrated ones.
                          NLT:  faithful people
New Bible Commentary, p 518:  Consecrated - The word blends 'beloved(by God)' and 'devoted (to God)

God calls around him to be witnesses to his justice all those who have been faithful to him and whom he loves dearly - people who have faithfully kept their side of the covenant with God and whose sacrifices and worship are genuine.

V 6.

The heavens proclaim his justice,
for God himself is the judge.

The Message:  The whole cosmos attests to the fairness of this court,
that here God is judge.

NIV: And the heavens proclaim his righteousness.

The 'heavens' - the spiritual world - also witnesses to God's suitability to be Judge.  The spirits, both those faithful to God and even those who rebel, all know that God has authority to judge. It is only here on earth that some people close their eyes to this fact.

New Bible Commentary, p 518.  If the heavens have witnessed human faults (v 4), they have also witnessed divine righteousness and can affirm the Lord's fitness to judge.

V 7.

Listen my people, and I will speak;
I will bear witness against you, O Israel:
I am God, your God

God re-inforces his authority - I am God, your God.  Once again, the use of repetitive language emphasises God's power and authority.  It is the title of the Redeeming God. (Exodus 20: 2-I am the Lord your God who brought you out of Egypt, out of the land of slavery)

God calls us to listen to him and to take notice of his accusations against us.  It is only though this that we are convicted of our selfishness and self-centredness - our sin - so that we then have a chance to repent and ask forgiveness.

V 8.

shall I not (or: I will not) find fault with your sacrifices,
though your offerings are before me always?

NLT: I have no complaint about your sacrifices
or the burnt offerings you constantly bring to my altar.

NIV: I do not rebuke you for your sacrifices
or your burnt offerings, which are ever before me.

God does not nit-pick about our sacrifices or forms of worship although this comment almost seems as if he might prefer to do without them!  In fact, our 'sacrifices' are more for our benefit than for God's.  The following verses of the psalm make it clear that God doesn't really need them - but we need to make them.  sacrifices are for our good.

New Bible Commentary, p 518.  Ritual formalism, those who revelled in the sacrifices but mistook their purpose, thinking that by them they were somehow enriching God and failing to live responsively to God in thanksgiving, obedience and reliant prayer. The Lord cannot rebuke what he commanded and as far as the material of sacrifice is concerned there is nothing to rebuke.  The ritualist is always punctilious.
 

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V 22.

Think well on this, you who forget God;
or I will tear you in pieces and no-one shall save you.

Forgetting God is the ultimate crime (sin).  There is no chance for those who ignore God.  This is the 'unforgivable sin' 
This reminds me of things that  Jesus said: 
(Luke 12: 10b)  ....for him who slanders the Holy Spirit there will be no forgiveness. (NLT: ...anyone who speaks blasphemies against the Holy Spirit will never be forgiven)
(Matthew 10: 33) and whoever disowns me before men, I will disown him before my Father in heaven
(John 3: 18) ....but the unbeliever has already been judged in that he has not given his allegiance to God's only Son. (NLT: But those who do not trust him have already been judged for not believing in the only Son of God)
These sayings used to bother me greatly as I couldn't reconcile in my mind the idea that a loving God would refuse to forgive anyone.  Then, one day it occurred to me that it isn't God who refuses to forgive, it's the unbeliever/slanderer who is incapable of receiving forgiveness!  How can a person accept forgiveness from someone they don't believe in?  Can't be done.  Those who deny God cut themselves off from the possibility of forgiveness.

V 23.

He who offers a sacrifice of thanksgiving
does me due honour,
and to him who follows my way
I will show the salvation of God.

Here is the other side of the coin - the promise of salvation for those who believe and give God genuine praise and worship and who live their lives in obedience to his will.
Note: The psalm was written before Christ came to make salvation a free gift for all who accept it.  We no longer have to earn our salvation by our actions, but we are still asked to live in obedience to God and, if we truly love him, we will want to please him by doing that.