Holy is The Lord
This is an enthronement psalm that pictures the Lord taking up His Davidic throne and ruling the earth from Jerusalem. The main point of this psalm is that the Lord is holy and should be exalted.
The first section of the psalm introduces the idea: Our Holy God is Great (99:1-3). All the peoples of the earth are instructed to tremble because the Lord reigns (99:1). God is the sovereign King of the Universe, and one day will rule His creation from Zion (99:2). Everyone should exalt the Lord for He is great, and praise His holy name (99:2-3).
The second section continues with the thought: Our Holy God is Just (99:4-5). God loves justice, and His strength is exerted in establishing what He loves (99:4). At His return the Lord will establish and sustain a just and righteous society over all the earth (99:5).
The third section continues with: Our Holy God is Merciful (99:6-9). God responded to the cries of His priests that cried out on behalf of the people (99:6). He gave them His Law, which governed the behaviour of His people so that they would be a holy people (99:7). Even when they continually went astray, God forgave them. Yet the consequences of their sins they could not escape; for God is a just God (99:8).
Brethren, three times the psalmist calls God “holy.” Three times all people are called to praise Him for His works and for His perfections. Our God is utterly different than anything in His creation. He is perfect and totally distinct from any created thing. He is great and awesome in His power. He is just and righteous in His actions. He is merciful in His love for His people, forgiving our sins.