God’s people need each other to grow spiritually. Over and over again the New Testament stresses that every believer is a part of the body of Christ. No body part can survive alone and say that it has no need of the other body parts. This is made crystal clear in the Bible. (1 Corinthians 12)
1 Timothy 2:5 said that there is one mediator between God and man the man Jesus Christ. Because of Jesus’s life death and resurrection there is no longer a need for an earthly priest to mediate between God and men. Jesus himself is our mediator. He is a priest forever in the order of Melchizedek always living to make intercession for his people. Read the book of Hebrews to better understand this.
1 Peter 2 talks about believers becoming living stones built into a spiritual house and becoming a holy priesthood themselves. Believers through Jesus become a chosen people, a royal priesthood, a holy nation, God’s special possession to declare the praises of him who called you out of darkness into his wonderful light.
House churches gather and meet together for this very purpose. To allow all of God’s people to declare his praises not just a few. God inhabits the praise of his people. The rocks must be crying out in many places of worship because God’s people are not allowed to praise him. Someone else is doing that for them. If they are allowed to praise God it is only through a hymn they sing selected by someone else in advance.
The Protestant reformers rightly focused on 1 Peter 2 to evoke the reformation. Though they embraced it theologically they did not embrace it by and large practically. What Protestants of all stripes and persuasions implemented in their churches were practices that were very similar to what they were protesting in the Catholic tradition? The reformers left designated clergy in control of the meeting of God’s people and substituted the preacher for the priest and the sermon for the mass.
The reformers talked about the priesthood of the believer and embraced the concept theologically but failed to implement it in their meetings. Why? I think there are a couple of reasons. One to support a professional clergy a congregation needs to be of substantial size to pay a professional minister. So the clergy wanted large gatherings to support them financially. Two to equip the laity to function on their own would work them out of a job. Once functioning on their own a congregation would no longer need them.