Worshiping a Benevolent (Yet Scary) God

At church this morning, the pastor talked about how heaven will be a place where multitudes of people praise and worship God.  I'm not sure to what extent I identify with this.  I know that I have good memories of praise and worship.  But what should be the focus of my worship?  God forgiveness of sins?  God creating a glorious universe?  God being superior to me?  God defeating evil and renewing the cosmos?  God's goodness, love, and compassion? 

I thought some about worship in my daily quiet times this past week.  I'm currently going through the Book of Exodus.  In Exodus 4:30-31, Moses shows signs to Israelites, and they then worship God because they realize that God has heard and will soon answer their prayers for deliverance from crushing slavery.  Worship here appears to be gratitude towards God----happiness at the good things that God does (or will do).  In Exodus 5, however, the faith of the Israelites (including Moses) is put to the test when the Pharaoh increases their work-load.  Moses then complains before God about the situation becoming worse and also his own (Moses') inadequacies.  Moses and the Israelites were not in a particularly worshipful mood then.

But, when Moses is speaking to the Pharaoh, Moses talks about another incentive to worship: "The God of the Hebrews hath met with us: let us go, we pray thee, three days' journey into the desert, and sacrifice unto the LORD our God; lest he fall upon us with pestilence, or with the sword" (Exodus 5:3 KJV).  In this case, God appears to threaten the Israelites to worship him, or else.  Worship and honor is something that the Israelites owe to God, in this scenario, and it occurs through the outward act of sacrifice.  Worship can be heartfelt gratitude in Exodus, but it is also giving God his due out of a sense of fear.  In the Book of Exodus, God appears beneficent and also, well, scary.