What is the house of God?

In the essay A conspiracy of Silence, Soon to End, Watchman says
that “Christendom does not constitute a spiritual house of God." Could you please define what constitutes a spiritual house of God? Also, why does the Watchtower constitute a spiritual house of God and Christendom doesn’t? Do they not both utilize the Bible to teach moral and biblical concepts, and having roots in Judaism? What is it that makes Jehovah’s Witnesses the spiritual house of God to the exclusion of everyone else? In all honesty is not Christendom, including Jehovah’s Witnesses, a reflection of ancient Israel and Judah in terms of our moral and spiritual condition before God?
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Strictly speaking the spiritual house of God is the congregation made up of anointed Christians. For example 1 Peter 2:4-5 says: “Coming to him as to a living stone, rejected, it is true, by men, but chosen, precious, with God, you yourselves also as living stones are being built up a spiritual house for the purpose of a holy priesthood, to offer up spiritual sacrifices acceptable to God through Jesus Christ.”

Peter also referred to the house of God being the first to experience God’s judgment even though many if not most of the individual members of the household are faithful and obedient to the good news, saying: “For it is the appointed time for the judgment to start with the house of God. Now if it starts first with us, what will the end be of those who are not obedient to the good news of God?”

Paul's writings at Hebrews 10:19-21 indicate that Jesus is a great priest over the house of God: “Therefore, brothers, since we have boldness for the way of entry into the holy place by the blood of Jesus, which he inaugurated for us as a new and living way through the curtain, that is, his flesh, and since we have a great priest over the house of God…”

In a broader sense the house of God may include the earthly organization that has come to be tightly grouped around the anointed house of God. That is reflected in the name given the administrative headquarters for Jehovah’s Witnesses known as Bethel; which means in Hebrew, the house of God.

Reasonably, the house of God is a single organization composed of fellow believers. It cannot be a collection of different denominations and sects. And one of the distinguishing features of the house of God, or the house of Israel, as it is sometimes called, is that each member of the household personally knows Jehovah. Quoting from the prophecy of Jeremiah Paul indicated that Christianity was the new house of Israel under God’s new covenant, when he wrote: "'For this is the covenant that I shall covenant with the house of Israel after those days,’ says Jehovah. ‘I will put my laws in their mind, and in their hearts I shall write them. And I will become their God, and they themselves will become my people. And they will by no means teach each one his fellow citizen and each one his brother, saying: 'Know Jehovah!' For they will all know me, from the least one to the greatest one of them."

Although the new covenant has not yet produced a people who all know Jehovah in the absolute sense intimated by the prophecy, it should be apparent that one of the fundamental requirements for membership in God’s household is a basic knowledge of him. The doctrines of Christendom effectively prohibit anyone under their influence from truly knowing God. To illustrate the point, the vast majority of churchgoers believe that Jesus is Almighty God; when the Bible plainly teaches that Jesus is God's son and has always been subject to God. Obviously, persons who believe such things cannot really know God.