“The mountain” in many places in the bible is the meeting place between God and man, and the mountain being described in the focus verse is a direct reference to the church, the mountain of the house of God (Isaiah 2:2), Mount Zion (Hebrews 12:22). And something distinct about the church, in the verse, is that the hand of God rests on the mountain.
The hand stands for various things. It stands for the move of God, the acts of God, the power of God.
Move of God
You do not get contact with God expect in the context of his church. We are the body of Christ (Ephesians 4:12), and Christ is one; the church is the bride of Christ (Ephesians 5:22-33), the body of God. That speaks of intimacy, oneness.
We do not know God apart from the church. And that calls for humility. The people of the church needs to lead you into truth, just as mighty Paul needed simple Ananias to guide him to truth (Acts 9:1-17).
The people who speak the word of God are the people of God. The church is the place of truth, any other place and we have lies (1Timothy 3:15). When God wanted to communicate the truth of the gospel to Cornelius, it was not the job of an angel, not even the job of the Holy Spirit in a direct sense, it was a job for Peter, one of the leaders of the church (Acts 10).
When persecution began in Jerusalem where the church was largely domiciled in its first few years, the Christians were spread abroad and as they went they took the message of the gospel with them and many became saved in the places where they went.
If nobody shared the good news, people will not be saved (Romans 10:13-16). People are not saved by default, they are on the way to hell by default. And they need an intervention of the gospel that can only come from the church.
It was the church, the Christians that Paul said they should have their feet shod with the preparation of the gospel of peace (Ephesians 6:15). People will remain restless without peace with God, expect the church reaches out to them in one form or the other, therefore our feet are the feet of Christ to reach to people in the different places in the world.
We communicate his love, or else the world will not know it. Jesus is once set free by his body (the church) and limited by her. He is confined to her, committed to her, and she is committed to him, to his mission. She carries on his mission, otherwise it would not be done. That is how serious being the body of Christ is.
In the book of the Song of Solomon, there was this mountain of spices and the wind was asked to blow on it and spread the fragrance (Song of Solomon 4:16). And using that analogy, Paul said that through him the fragrance of the knowledge of Christ is spread to the Gentiles (2Corinthians 2:14). The Holy Spirit commissioned him and Barnabas to the reach the gentiles (Acts 13:1-5). Without that, those people are condemned to be eternally lost. The duo were God’s mercy extended.
The acts of God
Where the hand of God is where the acts of God are seen, there is the manifestation of the glory of God in the church which makes things happen.
When Jesus did miraculous, for example in the turning of water into wine, it was put to the manifestation of the glory of God. When he turned water into wine in the wedding in Cana of Galilee, John recorded that was the beginning of miracles and Jesus manifested his glory and his disciples believed him (John 2:1-11). In another place we read that without signs and wonders people will not believe (John 4:48). The psalmist said: by terrible things in righteousness, God will answer us (Psalm 65:5).
The power of God
It takes the power of God to get people saved. We know that those who are not saved are kept in bondage by the devil (2Corinthians 4:4), not willingly, but they are slaves to sin and by extension to dead and by further extension to the devil, who rules by the power of death.
Miracles were usually associated with people getting saved in the book of Acts. While a few people are converted through the ministry of Paul took the intellectual route, in the ministry of Philip in Samaria, mammoth crowd believed in Jesus, because of the display of miraculous power. However there are miracles in the ministry of Paul but they are not associated with large numbers of people becoming into salvation, like the miracles through Peter and Philip.
Speaking in favour of the demonstration of the miraculous power of God, Paul said that he does not want the faith of the people to rest in the wisdom of men but in the power of God, which is a much better foundation (1Corinthians 2:1-5). So while Peter and Philip were committed to miracles to bring people to Christ, Paul was committed to miracles to deepen the commitment of believers to Christ.
Jesus associated having greater devotion to him with the manifestation of power in his name. When his disciples came to him that someone was casting out devils in his name, asking if they should stop him, he said they should leave him alone because no one can perform miracles in his name and soon after turn his back on him, deny him (Mark 9:38-39).
That is why Jesus encourages all of us to be miracle workers. Manifesting his power, deepens our understanding of him and our attachment to him and conviction about him. Miracles bring his reality closer to us, and it becomes hard to convince us against his truth. Jesus said those who believe in him will cast out devils, the will lay hands on the sick and they will recover (Mark 16:15-18). These are manifestation of the power of God which all confirms that the hand of God rests on his mountain.
The mountain is elevated, it is the place of elevated existence, of spiritual life, of the higher life. To experience a mountain, you do not just look at it, you have to climb it.
It is the place where we gain a new view of things, but the climb can be rigorous. And the climb is to the height of the power, acts and move of God. But climb we must because we will not rest until we have the fullness of God.