What is the Church of Christ?

The Definition of a Church

The church is not the building, it is the people who come together in close fellowship to worship Christ.  It is based on a promise of Jesus that when people gather together in his name that he would be present in their midst.  The communion is the breaking of bread and sharing of wine that we do in remembrance of His love and sacrifice, to be one body in Christ and for remission of sins.  Worship can be in silence or traditional praise with songs and dance as the Israelites did to celebrate the Lord and for his goodness and providence.

Matthew 18:20 For where two or three are gathered together in my name, there am I in the midst of them.

1 Corinthians 12:12 For as the body is one, and hath many members, and all the members of that one body, being many, are one body: so also is Christ. 13 For by one Spirit are we all baptized into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit. 14 For the body is not one member, but many.

Luke 22:17 And he took the cup, and gave thanks, and said, Take this, and divide it among yourselves: 18 For I say unto you, I will not drink of the fruit of the vine, until the kingdom of God shall come. 19 And he took bread, and gave thanks, and brake it, and gave unto them, saying, This is my body which is given for you: this do in remembrance of me.

2 Thessalonians 2:15 Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.

Is singing a tradition, did Jesus sing?

Yes, praise and worship is a form of praise. From Torah in the old testament to Jesus in the New Testament they sang and used musical instruments of worship. David danced before the lord, and Solomon had organised an excellent choir with musical instruments and praise and worship. 

Exodus 15:1 Then Moses and the Israelites sang this song to the Lord

2 Samuel 6:14 Wearing a linen ephod, David was dancing before the Lord with all his might, 15 while he and all Israel were bringing up the ark of the Lord with shouts and the sound of trumpets.

2 Chronicles 6 The priests took their positions, as did the Levites with the Lord’s musical instruments, which King David had made for praising the Lord and which were used when he gave thanks, saying, “His love endures forever.” Opposite the Levites, the priests blew their trumpets, and all the Israelites were standing.

Psalm 95:1 Come, let us sing for joy to the Lord; let us shout aloud to the Rock of our salvation. 2 Let us come before him with thanksgiving and extol him with music and song.

Mathew 26:30 And when they had sung an hymn, they went out into the mount of Olives.

Why the Church of Christ does not convene on Sabbath?

In general Christians day of prayer and worship is Sunday, the Jews customarily observe Sabbath as Saturday. 

Mark 2:27 And he said unto them, The sabbath was made for man, and not man for the sabbath: therefore the Son of man is Lord also of the sabbath.

When do we celebrate the birth, death, resurrection of Jesus and festive days?

Christmas denotes the birth of Jesus,  there are two supporting evidences in the Bible, it coincides with the Roman Census under Caesar Augustus, and the appearance of the star of Bethlehem, both of which  have no provided historical records or significant dates.  It is therefore assumed that the church simply celebrates and consecrated it in remembrance of Jesus.  Similarly, the death of Jesus coincides with Passover, as he was crucified a day before the sabbath during passover, so the church commemorates his death and resurrection on Easter.  There are other days celebrated like Jesus raised to heaven in 40 days when we celebrate Ascension Day and the disciples receiving the Holy Spirit termed Pentecost.  These are arbitrary in nature but as most other religions we commemorate these days in remembrance and celebrate the life, death and resurrection of Jesus and other important events.

Luke 2:4 And Joseph also went up from Galilee, out of the city of Nazareth, into Judaea, unto the city of David, which is called Bethlehem; (because he was of the house and lineage of David:) 5 To be taxed with Mary his espoused wife, being great with child.

Mathew 2:9 When they had heard the king, they departed; and, lo, the star, which they saw in the east, went before them, till it came and stood over where the young child was.

John 18:28 Then led they Jesus from Caiaphas unto the hall of judgment: and it was early; and they themselves went not into the judgment hall, lest they should be defiled; but that they might eat the passover.

Acts 1:3 To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God:

Acts 2:2 And when the day of Pentecost was fully come, they were all with one accord in one place. (Pentacost = 50th day, 49 days after passover)