1. God is the Great Savior
The first time we see reference to God and the term "great" in the same verse is in Exodus 14:30-31 "Thus the Lord saved Israel that day from the hand of the Egyptians, and Israel saw the Egyptians dead on the seashore. 31 When Israel saw the great power which the Lord had used against the Egyptians, the people feared the Lord, and they believed in the Lord and in His servant Moses." When Israel saw their enemies defeated, they saw in one event not only an end to their slavery, but also God defeat what Pharoah represented: the array of gods and goddesses worshipped by the Egyptians, the wealth and power of that nation and four centuries of tyranny wiped away in one night! When we come to the New Testament, Jesus is deemed the Great God and Savior in Titus 2:13 "looking for the blessed hope and the appearing of the glory of our great God and Savior, Christ Jesus." Indeed God is great! God is the Great Savior!
2. God is great because He is God
Sometimes the distinction is made between praise and worship, in that "praising God" has to do with what He does, whereas "worshipping God" deals moreso with the kind of God He is. Although pressing such a distinction can go to far, it nevertheless helps us in being reminded of the fact that God's greatness in Who He is in His being defines His greatness, followed by what He does. Deuteronomy 10:17 states: "For the Lord your God is God of gods, and Lord of lords, a great God, a mighty, and a terrible, which regardeth not persons, nor taketh reward." (KJV) God is the "Great God" because He literally is the Only God in a class by Himself by virtue of His majestic being (God of gods), His majestic authority (Lord of lords) and that is mighty and to be feared (translated here in the KJV by the term "terrible"). God is depicted in Deuteronomy 10:17 as a God that is just and fair in his dealings with people (literally in the Hebrew "not preferring one person over another" or the KJV "regardeth not persons") and One who is not moved by bribes. God is clearly not like human beings in the sense He is not molded by circumstances nor capable of having His hand forced to bend to anyone's will. God is God. Numbers 23:19 “God is not a man, that He should lie,Nor a son of man, that He should repent; Has He said, and will He not do it? Or has He spoken, and will He not make it good? God is great because He is, well, God." Malachi 3:6 “For I, the Lord, do not change; therefore you, O sons of Jacob, are not consumed." Hebrews 13:8 states similarly - Jesus Christ is the same yesterday and today and forever." The God of the Bible is great. He is great because He is the Great Savior and because He is God.
Worship and praise are the spill over of fervent love for God for all He is and what He has done. At first when we read Psalm 95:3, we may be tempted to think the Psalmist is contrasting God as the greatest among many - "For the Lord is a great God, and a great King above all gods." However as you read on into the Psalm, Yahweh is affirmed as having formed every square inch of creation, which by default makes all other would "god" nothing more than non-existent, non-living idols of men's imaginations. Consider Psalm 95:4-6 "In his hand are the deep places of the earth: the strength of the hills is his also. 5 The sea is his, and he made it: and his hands formed the dry land. 6 O come, let us worship and bow down: let us kneel before the Lord our maker." Proverbs affirms this role of the Great God as the Creator having the right to render judgment in Proverbs 26:10 "The great God that formed all things both rewardeth the fool, and rewardeth transgressors."
Any God that can do all these things and Be powerful enough, knowledgable enough and present enough in the past, present and future is more than worthy of our worship. God is Great. God is the Great Savior, great because He is God and worthy of worship. It would seem at this point we have reached the summit of this mountain of truth concerning the fact that "God is great". However what is the purpose of climbing any mountain? To see glories and wonders that can never be viewed on the ground. Only one more thought can complete today's study concerning why God is so great, namely...