I don’t keep the feasts listed in Leviticus 23 while my friend who is in the United Church of God does. My pastor says we would have to keep all the Old Testament laws if we are to keep those feasts. Why is it necessary, since we don’t sacrifice anymore

Are the Old Testament feasts to be kept?

You have asked some good and far-reaching questions.

In brief, the United Church of God observes the festivals outlined in Leviticus 23 because they were commanded by God in the Old Testament and that command was never abrogated in the New Testament. In fact, Jesus Christ observed them, as did His apostles and the New Testament Church long after His death (Luke 22:15And he said unto them, With desire I have desired to eat this passover with you before I suffer:
See All...; 1 Corinthians 5:6-8 [6] Your glorying is not good. Know ye not that a little leaven leaveneth the whole lump?
[7] Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us:
[8] Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with the unleavened bread of sincerity and truth.

See All...; Acts 2:1And when the day of Pentecost was fully come, they were all with one accord in one place.
See All...; 18:21; 20:16). We should follow their example (1 John 2:6He that saith he abideth in him ought himself also so to walk, even as he walked.
See All...; 1 Peter 2:21For even hereunto were ye called: because Christ also suffered for us, leaving us an example, that ye should follow his steps:
See All...; 1 Corinthians 11:1Be ye followers of me, even as I also am of Christ.
See All...).

In introducing His command to keep these festivals, God makes an important point: "These are my appointed feasts, the appointed feasts of the Lord, which you are to proclaim as sacred assemblies" (Leviticus 23:2Speak unto the children of Israel, and say unto them, Concerning the feasts of the LORD, which ye shall proclaim to be holy convocations, even these are my feasts.
See All..., New International Version, emphasis added throughout).

Most people assume these feasts are only for the Jews. Yet God clearly tells us they are His feasts, not the feasts of any particular ethnic or religious group. Further, He says they are His "sacred assemblies"— appointed times or divine appointments when He commands His people to gather before Him.

One of the major flaws in mainstream Christianity today is how the Old Testament or Hebrew Bible is generally viewed. Over the centuries there has been an enormous effort to cut Christianity off from its roots by claiming that much of the Old Testament is no longer applicable or necessary to the Christian life. Yet the New Testament itself emphasizes the importance of the Old Testament.

Consider what the apostle Paul wrote to Timothy: ". . . From childhood you have known the Holy Scriptures, which are able to make you wise for salvation through faith which is in Christ Jesus. All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work" (2 Timothy 3:15-17 [15] And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus.
[16] All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:
[17] That the man of God may be perfect, throughly furnished unto all good works.

See All...).

There was no New Testament canon when Timothy was a child. The "Holy Scriptures" to which Paul referred were what is today commonly called the Old Testament. Far from being obsolete or unnecessary, Paul says these words are "given by inspiration of God" and "profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man [or woman] of God may be complete, thoroughly equipped for every good work."

Marvin Wilson, professor of biblical and theological studies at Gordon College, Wenham, Massachusetts, lamented the general state of Christian knowledge of the Old Testament in our modern age:

". . . Many Christians seem to have little knowledge about their biblical roots [in the Hebrew Bible]. They have never really penetrated the inner world of biblical thought. Christians can converse intelligently about the latest automobiles, fashions, music and sports, but too few give evidence of a deep understanding of their spiritual heritage. At best, their grounding in biblical soil is both shallow and shaky . . . Churches have conveyed the attitude that a thorough understanding of this [Old] Testament . . . is, more or less, optional for today's Christian" ( Our Father Abraham, 1989, pp. 4-5, 108).

The New Testament mentions Jesus, the apostles or members of the early Church observing six of the seven annual feast days. Only the Feast of Trumpets is not mentioned. But the event that this particular annual Holy Day heralds—Jesus Christ's return—is mentioned prominently in the New Testament.

What few people realize is that these biblical festivals teach us the major steps in God's plan for the salvation of mankind. Passover, for example, foreshadowed the sacrificial death of Jesus Christ as the Redeemer of mankind (1 Corinthians 5:7Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us:
See All...)—which took place on the very day of the Passover. The Feast of Unleavened Bread depicts the necessity of Christians to remove sin from their lives and live a new, sinless life in Christ (verses 7-8).

The Feast of Pentecost, also called the Feast of Firstfruits, foreshadowed the founding of Jesus Christ's Church, made up of those who are the firstfruits in God's plan of salvation (James 1:18Of his own will begat he us with the word of truth, that we should be a kind of firstfruits of his creatures.
See All...; Revelation 14:4These are they which were not defiled with women; for they are virgins. These are they which follow the Lamb whithersoever he goeth. These were redeemed from among men, being the firstfruits unto God and to the Lamb.
See All...). And, not coincidentally, God founded that Church on the Feast of Pentecost when He sent His Spirit to the 120 disciples gathered in Jerusalem (Acts 2). In every sense these are truly Christian Holy Days, as they revolve around Christ's role in God's plan.

If you would like to read more about all of the annual biblical festivals and their meaning, we suggest you read our booklet God's Holy Day Plan: The Promise of Hope for All Mankind .

Observance of the Holy Days does not obligate us to keep the law of sacrifices today. Indeed, since the destruction of the Jerusalem temple in A.D. 70, there is no Levitical priesthood to offer them or a place designated by God at which they can be offered.

Even if we did have a temple and a priesthood, sacrifices would not be required for Christians today because the one great sacrifice of Christ made the need for animal sacrifices redundant during this Church age (Hebrews 9:11-14 [11] But Christ being come an high priest of good things to come, by a greater and more perfect tabernacle, not made with hands, that is to say, not of this building;
[12] Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption for us.
[13] For if the blood of bulls and of goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh:
[14] How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?

See All...; 10:1-14). This is one of the major points expressed in the book of Hebrews.

Animal sacrifices were part of the administration of the affairs of the physical nation of Israel, whereas today the Church is a spiritual nation called "the Israel of God" (Galatians 6:16And as many as walk according to this rule, peace be on them, and mercy, and upon the Israel of God.
See All...). The apostle Peter made it clear that the Church is "a spiritual house, a holy priesthood, [called] to offer up spiritual sacrifices acceptable to God through Jesus Christ" (1 Peter 2:5Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ.
See All...).

Those sacrifices include our prayers to God as well as the presentation of our lives as a living sacrifice (Romans 12:1I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.
See All...). This latter expression refers to a life that is dedicated to living God's way and keeping His laws.

This is a rather broad subject, and this answer has hit only some of the high spots. Please be sure to request the free booklet God's Holy Day Plan: The Promise of Hope for All Mankind . Also ask for Jesus Christ: The Real Story , as it will make plain Christ's teachings on the necessity of observing God's law.