The answer is obvious. It was a church when it began in the house. If it had continued to meet in a house, it would have continued to be a church.
God is stirring and shaking our present church structures and bringing us back to basics. Much of what we now have come to think of as essential is not really essential at all.
When we look at the simplicity of the New Testament Church and compare it with the institutionalized church of our day we see little, if any, resemblance.
The Church in some countries looks more like a corporation. Some denominations are huge networks that, in many cases, are ruled over politically, rather than through God-ordained spiritual authority. This has caused immeasurable grief and division for hundreds of years.
May God give us the insight, humility and grace to admit how far we have strayed from the simplicity and the purity of the New Testament Church. Then let us return to it in brokenness and repentance.