The Church as "the house" and as "the body of Christ" began on the day of Pentecost. Acts, chapter 2, records the way in which it took place; and 1 Cor. 12:1313For 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 Corinthians 12:13), tells us that all were then baptized by ONE SPIRIT into ONE BODY.
This was a "saved remnant" from among the Jews, to which was afterward added the Gentiles in Acts, chapter 10. This was fulfilling the word in John 10:1616And other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd. (John 10:16), which is correctly rendered "one flock," and also the word in chapter 11:52, which speaks of the gathering together "in one" the children of God that were scattered abroad.
We may get bad material when the Church is viewed as the house, for man may add that which is not real; but all is good material when it is the body, for it is the Holy Spirit that unites to Christ in glory.
LORD JESUS! are we one with Thee?
O height! O depth of love!
And crucified and dead with Thee,
Now one in heaven above.
Such was Thy grace, that for our sake
Thou didst from heaven come down;
With us of flesh and blood partake,
And make our guilt Thine own.
Our sins, our guilt, in love divine,
Confessed and borne by Thee;
The gall, the curse, the wrath were Thine,
To set Thy ransomed free.
Ascended now, in glory bright,
Life-giving Head Thou art;
Nor life, nor death, nor depth, nor height,
Thy saints and Thee can part.
And soon shall come that glorious day,
When, seated on Thy throne,
Thou shalt to wondering worlds display
That we with Thee are one.