“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.”" ( 1 Cor 12:13 KJV)
It is hard to disagree with someone who holds to the idea of "sola scriptura" and that everything that must be believed must be in the Bible. You have a limited understanding of Christian history. I don't blame you for leaving the Catholic faith. The Catholic Church, according to Scott Hahn, a convert to the Catholic faith, did a wretched job of catechizing people over the last 200 years. I cannot begin to tell you how many Roman Catholics I have met in my lifetime who were abysmally ignorant of their own faith, the Fathers of the Church, and Christian history in general. They, like you, were easy prey for the various Protestant sects and the cultists such as the JW's and Mormons.
Your problem, as I skimmed the lengthy posts you made, is that you twist the Scripture mean what your chosen denomination has told you that they mean. The rather humorous part, as I said before, is that you can find probably three or four dozen equally vocal and dedicated Protestants from other assemblies who would vehemently disagree with you and would use the Scriptures to do so. Do you see the problem here? Is the Holy Spirit that schizophrenic?
Regarding your quote above, to whom do you answer in matters of Christian doctrine and morality? If a SDA member tells you that A.) he is in the Church because he believes in Christ, and B.) that you must worship on Saturday, does he have the authority over you to tell you this? After all, according to your thinking, he is in the Body of Christ as one who professes Christ, and therefore, perhaps he has authority to tell you what to do.
As regards the Church, let's make a few suppositions here:
1. The Church is the Body of Christ in the New Covenant. That means that Christians are people of the Covenant of God.
2. The Church existed in the Old Covenant. The word "church" is ἐκκλησία
ekklēsia in the Greek and עֵדָה
ʿēḏâ (literally "congregation") in the Hebrew. In this sense, one could have a "congregation" in a house, as in the house churches of the first century, or one could be speaking of the larger congregation.
3. In order to be part of the congregation, one has to enter into the covenant. In the OT that was done by circumcision, and the man who was not circumcised was considered to be outside of the congregation of Israel. The same applies to the NT congregation. Baptism is that act of "covenant cutting" which enters one into the congregation.
4. There are five active principles of covenant:
T - Transcendence "The greater offers covenant to the lesser."
H - Hierarchy "Who is in charge here?"
E - Ethics "What are the rules of the covenant."
O - Oaths and sanctions "Promises to keep the covenant ethics and sanctions upon disobedience."
S - Succession "The covenant is handed down from generation to generation."
The principle germane to our discussion is hierarchy. In any covenant structure, there is one who is the covenant head. Not many. One. St. Paul made mention of this when he spoke of his authority to those who were dismissing and insulting his leadership in his absence. He warned them that he could either come with love or a rod of correction.
There is no way to have one authority over thousands of independent assemblies who answer only to themselves. This is why there is chaos in Christendom today, with literally hundreds of different teachings within Protestantism, all contradicting each other, and yet all claiming to be following the Bible and the Holy Spirit. The earthly body can only have one headship, and that is the Last Adam - Christ. The Bible says that the Church is His Body, therefore, when the Church speaks Christ speaks, and when the Church is silent, we have no right to invent things such as the Filioque Clause to the Creed or Indulgences. Christ speaks through His Church, but when hundreds of denominations are speaking all different things and yet claiming to be "The Church" or part of the Church - this chaos simply cannot be true. God is not the author if confusion.
Our God is greatly merciful, and He works wherever and whenever He chooses to work. Contrary to those Fundamentalists in both Orthodoxy and Catholicism who claim that there is no salvation outside their assembly, Christ's mercy extends far beyond our limitations. I like that in Orthodoxy, a bishop recently said "We know where the Church is, but we do not know where it isn't" which speaks to our Lord's actions outside the boundaries of the physical Church.
Nonetheless, our Lord called for unity in John 17 and not division. We are to be guided by one Divine Head who speaks through His Church, the Orthodox Church, which has remained unchanged in doctrine for hundreds of years. It is this Church which called councils and established the truth against heresies such as Montanism, Gnosticism, Monothelitism, Monophysitism, and Arianism.
Finally, when the writers of the Scriptures spoke of the congregation, they had no idea of an invisible body of "true believers." They knew who the leaders were and who bore authority. They knew where the worship took place, and it was not out in the woods with the butterflies and bees. They also knew that there were established norms of worship which were important because they were given by God. A great deal of Evangelical worship today is nothing more than entertainment. Take the pictures of Jesus out of their building, take away the crosses, and you have a nice nightclub with good music. That's not worship. That is the flesh getting entertained.
The worship of Orthodoxy is over 1500 years old. As the Church came out of hiding, the worship developed along Scriptural lines. Here is how the Divine Liturgy meets all that Scripture says we should do:
Opening Doxology [“Blessed in the Kingdom…] Mark: 11:10; Luke: 22:29-30, Matthew: 28:19; Revelation: 7:12.
The Great Litany – Philippians: 4:6-7; Psalm 51:1 Luke: 18:13; John: 14:27; 1 Timothy: 2:1-2;
1 Hebrews: 13:7; Psalm 109:26; Luke: 1:42.
The First Antiphon – [“Bless the Lord, O my soul”]. Selected verses from Psalm 103.
The Second Antiphon – [“Praise the Lord, O my soul”]. Psalm 103.
The Hymn to Christ Incarnate – [“Only- begotten Son…,”]. John: 1:1, 3:16, 17:5, 19:18; Luke: 1:35; Hebrews: 2:14; Matthew: 8:25.
The Third Antiphon – [The Beatitudes] Matthew: 5:3-12.
The Little Entrance – [“Come let us worship..,] Psalm 95:1-6; Revelation: 7:11-12.
The Trisagion – [“Holy God, Holy Mighty…,”] Isaiah: 6:1-5; Revelation: 8:8.
Prokeimenon – Psalms 12:7,1; 28:9,1; 29:11,1; 33:22,1; 47:6,1; 76:11,1; 104:24,1; 118:14,18.
The Epistle – readings change daily, from the Epistles or Acts of the Apostles.
The Allelulia – Psalms 113:1; 135:1; 146:1; Revelation: 19: 1-6.
The Gospel – readings change daily. The Sermon – 1 Timothy: 4:13.
The Cherubic Hymn – [“Let us who mystically..”] Colossians: 3:12; Pslam 24; Revelations: 19:1-6.
The Great Entrance – Psalm 43:4; Matthew: 5: 23-24; Hebrews: 5:1.
The Peace – [“Peace be unto all…”]. John: 20: 9,21,26. 1 John 4:7; 1 Peter: 3:8; Philippians:2-2.
The Eucharistic Canon – [“Let us stand aright”] Leviticus: 3:1; Hebrews: 13:14-15; Hosea: 6:6; Psalm 49:19; Matthew: 9:13; Corinthians: 13:14; 2 Timothy: 4:22; Lamentations: 3:41.
The Eucharistic Prayer – [“Holy, Holy, Holy…” through the Consecration]. Isaiah: 6:3; Mark: 11:10; Matthew: 21:9; Corinthians: 11:23-24; Matthew: 26:26-28; John: 6:51; Luke: 22:20; Mark: 14: 23-24; Corinthians: 29: 14, 16; Romans: 21:1.
Hymn to the Theotokos – [“It is truly right…”]. Luke: 1:28, 42, 48.
The Concluding Eucharistic Prayers – 2 Maccabees: 12:44-45; 1 Timothy: 2:2; 2 Timothy: 2:15; Romans: 15:6; Titus: 2:13; Revelations:22:21
The Litany before the Lord’s Prayer – Ephesians: 5:2; Philippians: 4:18; 1 Peter: 3:15; Corinthians: 5:10; Ephesians: 4:13; Philippians: 2:1.
The Lord’s Prayer – Matthew: 6:9-13; Corinthians 29:11.
The Elevation of the Holy Gifts – [“Holy things are for the Holy.”] Leviticus: 11:44; Philippians: 2:10-11.
The Communion Hymn – [“Praise the Lord…”] Psalm 148:1.
The Eucharist – 1 Corinthians: 11:27-29; Matthew: 16:16; 1 Timothy: 1:15; Mark: 14:45; Luke: 23:42- 43; Isaiah: 6:7; 1 Timothy: 1:14; James: 4:8; Psalm 118: 26-27; Psalm: 34:8; 1 Peter: 1:19; John: 6: 32-35, 48-58; Psalm 116:13; Psalm 28:0.
Hymns after Holy Communion – [“We have received the true Light..”]. John: 1:9; Rev.: 3-14; Psalm 71:8; Chronicles: 16:9; Ephesians: 3:9.
Litany after Communion – Judges 18:6; Colossians: 3:17; Mark: 11:9.
Prayer behind the Ambo – [“O Lord, who blesses those who…”]. Genesis 12:3; Psalm 28:9, Psalm 26.8; Psalm 138:81, 1 Timothy: 2:2; James: 1:17.
“Blessed be the name of the Lord, from this time forth and for evermore!” Psalm 113:2.
“The blessing of the Lord…”. Psalm 129:8; 2 Corinthians 13:14.
The Dismisal – 1 Timothy: 1:1.
I encourage you to study Orthodoxy. It is the Church and the fullness of the Christian faith.