Worship
Ask many people what the main function of the church is, and you'll likely have a majority of them answer that it is for worship. This comes from a misunderstanding of the difference between the "church" (which is the people) and the "church building". Past that, most people don’t really know much about worship.
Today's idea of worship among some denominations is not anything like the worship of times past. It has changed with the culture of the day - which the church ought not to always do. While change may be good and even necessary in some things, worship is one of the core values patterned by God, and since God is non-changing, so ought to be our form of worshiping him. What passes today for worship is in many cases just a feel-good show, centered around fleshly human desires rather than on God.
To understand true worship, we must turn to God's Word. The first recorded instance would be found in Genesis 3. There we see in verse 21 that God made them clothing from animal skins, indicating a sacrifice of blood was performed for their sins. In chapter 4, we see Cain and Abel growing up, and bringing their sacrifices before God. Throughout the rest of the patriarchal age we see the great men of the Bible - Noah, Abraham, Isaac, Jacob - all bringing sacrifices before God for their families.
Then, during the time of Moses, God gave them a plan by which to worship. In the Law (which contained, but was not limited to, the Ten Commandments), God gave a pattern for worship, a pattern for the leaders of worship, a plan for the time of worship, and a plan for the place of worship. Exact specifications on all these things were given.
After the first temple was destroyed in Jerusalem, and the people of Judah were in captivity, there arose the practice of building the synagogue for worship purposes. There were some differences between the worship there and the worship in the Temple. Basically, in the synagogue, the people prayed, sang hymns (without the aid of instruments), gave of their means, and read from God's Word - listening to teachers who taught them from it.
Mosaic Law was only meant to be temporary, of course. In due course of time, God sent his Son, whom they called Jesus, to die and be the sacrifice for our sins. Since he died one time and that covers all sins should we obey the gospel (see "How Does One Become Saved?"), there is no longer any need for a sacrifice of animal to be given. The disciples began to gather together on the first day of the week to worship, and since this was their approved example in the New Testament, we follow suit today. They followed the same style of worship they had in the synagogue with one very important addition, the Lord's Supper (Communion). This addition was commanded by Jesus do be done in remembrance of him (1 Corinthians 11:24-25); the unleavened bread symbolizes his body, and the fruit of the vine (grape juice) symbolizes his blood. Thus we see that sacrifice is also a part of New Testament Worship.
The pattern followed by the disciples is thus:
Done on the first day of the week: Acts 20:7
Communion: Acts 20:7
A Capella Singing: Ephesians 5:19
Prayer: Acts 16:25
Giving of Means: 1 Corinthians 16:2
Preaching: Acts 20:9
Since this is how the disciples worshiped during the first century, we endeavor to follow that same example in our worship pattern today.