As the Baptist and Shorter Catechism says:
Q. What is the invisible church?
A. The invisible church is the whole number of the elect, that have been, are, or shall be gathered into one under Christ the head.
The purpose of the Church in the world is to worship and glorify God. The primary way the Church is to worship and glorify God is by the preaching of the Gospel. The mandate and commission that has been given by the Lord himself is to make disciples of all nations and administer the Sacraments of the Lord's Supper and Baptism. The ultimate goal, based upon the authority of Christ, is one of uniting all believers to God in one family.
The Church only accomplishes it's mission by gathering together regularly. This is why it is necessary to organize into local congregations. Or in other words, the only way to accomplish the mission given by Christ is by establishing local churches. The Church is represented visibly on Earth in the form of local societies, fellowships, communities, congregations and churches. The local Church is the company of those in a specific geographic area, who have decided to fellowship together on Sunday, the Lord's Day. It is where the Word of God is preached, and the Sacraments are rightly ministered, and involves all those things that are necessarily required to so.
The Baptist and Shorter Catechism again says:
Q. What is the visible church?
A. The visible church is the organized society of professing believers, in all ages and places, wherein the Gospel is truly preached and the ordinances of Baptism and the Lord’s Supper rightly administered.
Richard Hooker writes, "By the Church…we understand no other than only the visible Church. For preservation of Christianity there is not any thing more needful, than that such as are of the visible Church have mutual fellowship and society one with another. In which consideration, as the main body of the sea being one, yet into a number of distinct Societies, every of which is termed a Church within itself. In this sense the Church is always a visible society of men; not an assembly, but a Society. For although the name of the Church be given unto Christian assemblies, although the name of the Church be given unto Christian assemblies, although any multitude of Christian men congregated may be termed by the name of a Church, yet assemblies properly are rather things that belong a to a Church. Men are assembled for performance of public actions; which actions being ended, the assembly dissolveth itself and is no longer in being, whereas the Church which was assembled doth no less continue afterwards than before." (Book III, i, s. 14, Laws)
Another aspect of the Church should be considered here as well. I agree with the Nicene Creed when it says, "I believe in the One, Holy, Catholic, and Apostolic Church." That isn't the Roman Catholic Church. It's called "One" because it has one Lord, one faith, and one baptism. It is called "Holy" because the Holy Spirit dwells in it, sanctifying all its members and gives gifts of grace. It is called "Catholic" because it is universal, and holds at all times, in all places, and for all people, all of the truth about Jesus Christ. It is called "Apostolic" because it received its divine mission from Christ through his Apostles, and continues in the Apostles teaching and fellowship.
This may sound all well and good, but why all the division? Thomas Cranmer said in a letter to John Calvin, "One of the greatest evils of our time, is that the churches are so widely separated from each other. The body of Christ is torn asunder because the members are separated." Why is it like this?
The London Baptist Confession says, "The purest churches under heaven are subject to mixture and error; and some have so degenerated as to become no churches of Christ, but synagogues of Satan; nevertheless Christ always hath had, and ever shall have a kingdom in this world, to the end thereof, of such as believe in him, and make profession of his name." (LBC 26:3)
Article 19 of the 39 Articles indicates further exactly where the most error can be found in the Church, "As the Church of Jerusalem, Alexandria, and Antioch, have erred; so also the Church of Rome hath erred, not only in their living and manner of Ceremonies, but also in matters of Faith."The parables of our Lord clearly indicate that the visible manifestation of the Church contains both wheat and weeds, sheep and goats, good fish and bad fish, good slaves and evil slaves. So I would argue that although the Churches of Jerusalem, Alexandria, Constantinople, Antioch, and Rome have greatly erred, they are nonetheless still part of the visible Church in much the same way that the northern Ten Tribe Kingdom was part of Israel even though it was guilty of gross idolatry. The Church is not confined exclusively or restricted to any one group, organization, sect, or denomination within historic Christianity.
Although very fragmented and split, I look forward to the day when the prophecy of the Apostle Paul concerning the future unity of the Church will be realized.
"And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers; for the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ: that we henceforth be no more children, tossed to and fro, and carried about with every wind of doctrine, by the sleight of men, and cunning craftiness, whereby they lie in wait to deceive; but speaking the truth in love, may grow up into him in all things, which is the head, even Christ." - Ephesians 4:11-15 KJV
Notice that the reason why apostles, prophets, evangelists, pastors, and teachers are given is for the eventual unity of the Church. Jesus prayed, "That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me." - John 17:21 KJV
When this happens, when the Church is finally united, then the world will believe that Christ was sent from God. The great commission can only be finally accomplished by a united Church. Although division may be necessary for now, given the nature of the errors of the Orthodox and Roman Churches, it is nonetheless an evil situation. Let us pray that those groups and bodies that are in error would repent and that the Church would be one.
To conclude this post, I post a hymn by Samuel J. Stone.
The church's one foundation
is Jesus Christ her Lord;
she is his new creation
by water and the Word.
From heaven he came and sought her
to be his holy bride;
with his own blood he bought her,
and for her life he died.
Elect from every nation,
yet one o'er all the earth;
her charter of salvation,
one Lord, one faith, one birth;
one holy name she blesses,
partakes one holy food,
and to one hope she presses,
with every grace endued.
Though with a scornful wonder
we see her sore oppressed,
by schisms rent asunder,
by heresies distressed,
yet saints their watch are keeping;
their cry goes up, "How long?"
And soon the night of weeping
shall be the morn of song.
Mid toil and tribulation,
and tumult of her war,
she waits the consummation
of peace forevermore;
till, with the vision glorious,
her longing eyes are blest,
and the great church victorious
shall be the church at rest.
Yet she on earth hath union
with God the Three in One,
and mystic sweet communion
with those whose rest is won.
O happy ones and holy!
Lord, give us grace that we
like them, the meek and lowly,
on high may dwell with thee.