Yet God is the enthroned one! He is seated in heaven with all authority and power (verse 3). That God is the ruler of all creation is foundation for the theology of the Hebrew Bible. He is the creator and therefore he is sovereign over all creation. The point here is that God is capable of saving the Psalmist.
The psalmist combines the sovereignty of God with his holiness. If the writer is being unjustly oppressed, God must act according to his holiness and judge, bringing the oppressor to justice. Not only can God save him, he must do so because it is part of his character to act in holiness.
The Psalmist recalls the history of Israel, those who have trusted the Lord in the past (verse 4-5). The “fathers” likely refers to the general history of Israel, but especially the Exodus and Wilderness. When God saved Israel out of Egypt it was in response to their cries of oppression in Egypt. They were surrounded by their oppressors, they cried out to God and God answered their cry. The psalmist is therefore evoking the history of Israel. God has already acted on behalf of his people, the writer wants God to act once again to rescue him from violent oppressors.
This may be a hint of the circumstance of the psalm. While it is true David was often surrounded by his enemies, it is possible this psalm was inspired by the somewhat regular national crises in the later history of Israel and Judah, including the Exile. It is possible the worshiper is in Exile in Babylon, literally surrounded by his enemies. God seems to have abandoned him. In fact, the prophets regularly described the Exile as a divorce or separation of God and his unfaithful bride. The psalm could be used at virtually any time in Israel’s history until messiah comes (anticipating verses 27-31).
God therefore is capable of saving the worshiper because he is sovereign, he ought to do so because he is holy, and history shows that he has acted to save his people on any number of occasions. This is the “crisis” of the psalm: the worshiper is surrounded by troubles he cannot handle, he has cried out to God, but God has not answered him – yet he does not stop because he knows that God will not forsake him: God will certainly answer his plea.