I have a question regarding the practical application of royal priesthood in the upcoming kingdom of God. Recently I got to know one of the elder and preacher in the church. According to him, we are a royal priesthood (referring to I Peter 2:9) and the role of priest is to offer up Christ to our God during Lord's Supper on Sundays. We must have to bring the best among our real experiences of Christ (as a Burnt offering, Sin offering, Meal offering, Peace offering, Tresspass offering, etc.) during the whole week in our daily living and offer it to the God. That is the only way of worship which pleases God the Father in heaven. By doing this, we can develop our character as a priest to serve in the upcoming kingdom of God! It sounds as it is more advance and very practical teaching on worship but very complicated to follow it. To me, as a beginner in Christianity, I could not grasp his teaching. (He follows the teaching of Watchman Nee, I think). Could you please elaborate for me our role in the upcoming kingdom of God as a royal priesthood? Do I need to prepare myself as a priest to fit into the kingdom? Are the offerings mentioned in Leviticus going to be re-introduced during the Millennium Kingdom? What does this mean?
Watchman Nee deluded himself during his life on earth. He believed he received further revelations from the Lord and that God revealed by revelation certain truths to him. He taught a blend of doctrines found in various denominations. Instead of reviewing what is wrong with Watchman Nee's teaching, let's us look at the word of God and simple truths that are in there.
A Christian follows no man. He only follows God (I Corinthians 1:10-13). The Corinthians were trying to follow Cephas, Apollos, and Paul, using their names to distinquish themselves. But everything Paul, Cephas, and Apollos taught was all the same. They all taught Christ and did not differ in their beliefs. Therefore, we too should only claim to be of Christ and not follow anyone else. The elder you are talking to is a follower of Watchman Nee. He is no different than a Lutheran, Catholic, Seven Day Adventist, Mormon or Baptist who follow man made doctrines instead of looking to please God (Galatians 1:10).
The kingdom of God
The terms "kingdom of God" and "kingom of Heaven" refer to the same thing. See: "Are the kingdom of God & Heaven the same?" Also see: "Church is the Kingdom." Watchman Nee saw these terms as separate, but they are not.
I bring this up because you refer to the "upcoming kingdom of God" a few times. When we speak about God's Kingdom, when will it come? "Truly I say to you, there are some of those who are standing here who will not taste death until they see the Son of Man coming in His kingdom" (Matthew 16:28; also see Colossians 1:13). The Son of Man (Jesus) will come into His kingdom before people of that generation (2,000 years ago) would die. God's kingdom has already come. The kingdom is the church, as seen in Matthew 16:18,19 when the Lord declared, "I will build My church" and said to Peter, "I will give you the keys of the kingdom of heaven." In one statement it is called the church and in the very next, it is called the kingdom of heaven. We are looking forward to eternity with God, when Jesus turns over the current kingdom over to the Father "then comes the end, when He hands over the kingdom to the God and Father, when He has abolished all rule and all authority and power. For He must reign until He has put all His enemies under His feet" (I Corinthians 15:24-25). The kingdom (the church) is under Jesus' rule right now until the end of the world when he hands it all over to the Father.
The Lord's Supper
We do not offer up Christ for a sacrifice. Jesus willing offered himself up to the Father (John 10:17-18) as a sin offering (Hebrews 9:24–10:3; 13:10-14). That sacrifice was done only once. We no longer no offer up physical sacrifices of the Old Testament because Christ paid for our sins. "But this Man, after He had offered one sacrifice for sins forever, sat down at the right hand of God, from that time waiting till His enemies are made His footstool. For by one offering He has perfected forever those who are being sanctified. ... Now where there is remission of these, there is no longer an offering for sin" (Hebrews 10:12-14,18).
When we go before God and partake of the Lord's Supper it is to remember Him, that He sacrificed himself for us, and that He will return. "And when He had given thanks, He broke it and said, "This is My body, which is for you; do this in remembrance of Me." In the same way He took the cup also after supper, saying, "This cup is the new covenant in My blood; do this, as often as you drink it, in remembrance of Me." For as often as you eat this bread and drink the cup, you proclaim the Lord's death until He comes" (I Corinthians 11:24-26).
To claim we offer up Christ is the opposite of what the Bible said. Christ offered up himself and we partake to remember what He has done for us, not to proclaim what we have done for the Father.
We do offer up spiritual worship and sacrifice under the Law of Christ. We are told that our prayers go before God as a sweet-smelling aroma of incense (Revelation 5:8, 8:3-4; Psalms 141:2). We are living sacrifices in service to God. "Therefore I urge you, brethren, by the mercies of God, to present your bodies a living and holy sacrifice, acceptable to God, which is your spiritual service of worship" (Romans 12:1). Our bodies are a living and holy sacrifices. "And do not be conformed to this world, but be transformed by the renewing of your mind, so that you may prove what the will of God is, that which is good and acceptable and perfect" (Romans 12:2). To be a living sacrifice, we must conform to God's will and no longer be living for ourselves. Paul tells us in Ephesians 5:1-10 how to live as a living sacrifice: Do not live for the world of sin (verse 3-6), but walk as children of light, doing what is pleasing to the Father (verses 7-10). Another way we are living sacrifices is when we are baptized. "Therefore we have been buried with Him through baptism into death, so that as Christ was raised from the dead through the glory of the Father, so we too might walk in newness of life" (Romans 6:4). Service to God is our living sacrifice.
You asked, "Are the offerings mentioned in Leviticus going to be re-introduced during the Millennium Kingdom?" Offering spiritual worship to God does not prepare you for offering physical sacrifices of animals? When someone tries to bring back portions of the Old Law, it nullifies God's grace (Galatians 5:4). The Old Testament sacrifices and the temple were a mere shadow of what was to come (Hebrews 10:1-3; Colossians 2:16-17). It is the other way around, the physical sacrifices and worship in the Old Testament prepared people for the New Testament. They were examples (shadows) to lead us to Christ (New Testament). But now that we have Christ there will be no need for the Old Testament practices ever again. "Therefore the Law has become our tutor to lead us to Christ, so that we may be justified by faith. But now that faith has come, we are no longer under a tutor." (Galatians 3:24-25).
Because of Jesus sacrifice, we can go confidently in prayer before God on His throne because Christ died for us. "Therefore let us draw near with confidence to the throne of grace, so that we may receive mercy and find grace to help in time of need. … Therefore, brethren, since we have confidence to enter the holy place by the blood of Jesus, by a new and living way which He inaugurated for us through the veil, that is, His flesh, and since we have a great priest over the house of God, let us draw near with a sincere heart in full assurance of faith, having our hearts sprinkled clean from an evil conscience and our bodies washed with pure water" (Hebrews 4:16; 10:19-22). Notice that this is in the here and now and not in some future kingdom.
"And coming to Him as to a living stone which has been rejected by men, but is choice and precious in the sight of God, you also, as living stones, are being built up as a spiritual house for a holy priesthood, to offer up spiritual sacrifices acceptable to God through Jesus Christ. … But you are a chosen race, a royal priesthood, a holy nation, a people for God's own possession, so that you may proclaim the excellencies of Him who has called you out of darkness into His marvelous light; for you once were not a people, but now you are the people of God; you had not received mercy, but now you have received mercy. Beloved, I urge you as aliens and strangers to abstain from fleshly lusts which wage war against the soul. Keep your behavior excellent among the Gentiles, so that in the thing in which they slander you as evildoers, they may because of your good deeds, as they observe them, glorify God in the day of visitation" (I Peter 2:4-5, 9-12).
Notice the use of the present tense. We are currently serving God as a chosen race and a royal priesthood. We are a holy nation in the church. We currently are God's people while on earth. But how do we offer up spiritual sacrifices that are pleasing to God, as mentioned in I Peter 2:5? Peter explains it in I Peter 2:11-12. We are to abstain from fleshly lusts (sins), keep our behavior excellent before God and man, and to do good deeds. These actions are pleasing to the Lord. It is again a life in service to Him while on earth. You are not preparing yourself for the priesthood, you enter into the priesthood when you become a Christian.
The Millennium Kingdom
There is no mellnnium kingdom mentioned in the Bible. People tend to confuse some passages mentioned in Revelation, which are symbolic, and try to make them literal. Please see: Are there sacrifices during the millennium?
Keep on learning God's word. It is a wonderful thing when we dive into the Word of God and learn how to live our lives pleasing to Him. But don't mistake the teachings of men for God's teachings.