How should a Christian today celebrate the annual festivals observed by Jesus Christ and the apostles?

Most Christians today don't observe the seven festivals God calls "My feasts" (Leviticus 23:2). Here is how the United Church of God celebrates these meaningful festivals today

The Bible lists seven festivals to be celebrated each year (Leviticus 23), and the New Testament shows many examples of Jesus, His apostles and the Church of God celebrating them. The first, the Passover, is a memorial of the sacrifice of Jesus Christ for our sins. This is also when we renew our agreement to come under the blood of Jesus Christ, the perfect Passover Lamb, for the forgiveness of our sins. We approach this period of the year with deep spiritual introspection. We commemorate the Passover on the 14th day of the first month of the sacred year with a service based on the instructions of 1 Corinthians 11:23-28 [23] For I have received of the Lord that which also I delivered unto you, That the Lord Jesus the same night in which he was betrayed took bread:
[24] And when he had given thanks, he brake it, and said, Take, eat: this is my body, which is broken for you: this do in remembrance of me.
[25] After the same manner also he took the cup, when he had supped, saying, This cup is the new testament in my blood: this do ye, as oft as ye drink it, in remembrance of me.
[26] For as often as ye eat this bread, and drink this cup, ye do shew the Lord's death till he come.
[27] Wherefore whosoever shall eat this bread, and drink this cup of the Lord, unworthily, shall be guilty of the body and blood of the Lord.
[28] But let a man examine himself, and so let him eat of that bread, and drink of that cup.

See All... and the Gospel accounts of the New Testament Passover that Christ instituted.

This solemn service begins with a brief explanation of its purpose, followed by foot-washing (based on Christ's example and instructions in John 13). Then the minister gives an explanation of the symbols of the Passover, unleavened bread and wine, which represent the body and blood of our Savior. Each baptized member of the Church eats a small piece of the unleavened bread and drinks a small glass of the wine (Mark 14:22-24 [22] And as they did eat, Jesus took bread, and blessed, and brake it, and gave to them, and said, Take, eat: this is my body.
[23] And he took the cup, and when he had given thanks, he gave it to them: and they all drank of it.
[24] And he said unto them, This is my blood of the new testament, which is shed for many.

See All...). Passover is the only festival that does not also include a Holy Day (annual Sabbath).

The Feast of Unleavened Bread is symbolic of the Christian's responsibility to strive to live a sin-free life. We prepare for the Feast of Unleavened Bread by removing leaven and leavened products (bread or other baked items that are made with yeast, baking powder, baking soda or potassium bicarbonate) from our homes (Exodus 12:18-19 [18] In the first month, on the fourteenth day of the month at even, ye shall eat unleavened bread, until the one and twentieth day of the month at even.
[19] Seven days shall there be no leaven found in your houses: for whosoever eateth that which is leavened, even that soul shall be cut off from the congregation of Israel, whether he be a stranger, or born in the land.

See All...). We also do not eat bread products made with leaven during the seven days of the Unleavened Bread festival in keeping with God's instructions. Two of the most common commercial unleavened breads are Ry-Krisp and matzos. (Not all matzos are free of leaven, however, so one has to read the labels.)

This festival begins and ends with an annual Holy Day on which church services are held similar to the kind of services we hold on every weekly Sabbath. However, on each of the annual Holy Days, the messages focus on various aspects of the meaning of the day we are observing.

The meetings begin with congregational singing, followed by a prayer. After that, an elder or someone designated by the pastor gives a 10- to 12-minute message. This is followed by announcements and the collection of an offering (in accordance with Deuteronomy 16:16-17 [16] Three times in a year shall all thy males appear before the LORD thy God in the place which he shall choose; in the feast of unleavened bread, and in the feast of weeks, and in the feast of tabernacles: and they shall not appear before the LORD empty:
[17] Every man shall give as he is able, according to the blessing of the LORD thy God which he hath given thee.

See All...). (Offerings are not collected on the weekly Sabbath, because there are no instructions or examples of this in the Bible.) More congregational singing may follow, or a choir or musicians may present special music.

The main message lasts approximately one hour and is given usually by the pastor or an elder that he designates. Occasionally, we will use alternative formats, such as having two messages of equal length (around 40 minutes each), between which we have the announcement segment and congregational singing or special music. All of the messages provide guidance, encouragement and education to the membership, as well as help us worship God. The service ends with a final congregational hymn and a closing prayer.

The next two Holy Days are Pentecost (reminding us of the giving of the Holy Spirit and the founding of the Church of God) and the Feast of Trumpets (picturing the return of Jesus Christ). All Holy Days are high day annual Sabbaths, so Christians do not perform their regular work on them, resting in the same way that they do on every weekly Sabbath.

The Day of Atonement has a unique aspect to it, in that God instructs us to "fast" or to go without food and drink. "Afflicted in soul" (Leviticus 23:29For whatsoever soul it be that shall not be afflicted in that same day, he shall be cut off from among his people.
See All...) is explained in Vine's Expository Dictionary as meaning to humble oneself through fasting.

Most of the Holy Days are observed in local congregations, with the exception of the Feast of Tabernacles and the Last Great Day. Church members and their families gather in centralized locations for that entire eight-day festival season. We observe this main festival season of the year with daily church services, including those days that are not annual or weekly Sabbaths. This festival is also a time of great spiritual and physical enjoyment and includes programs for families, seniors, teens and young adults.

For more understanding please read our booklet God's Holy Day Plan: The Promise of All Mankind .