On the question of House Church giving, there are, at minimum, two different things under consideration here and they seem to be getting conflated:
1. There are people, Protestant and Catholic alike, who are technically affiliated with an ecclesiastical body, but who do not physically attend. For these, there are further breakdowns. Are they not attending because they are really unchurched? Or is there a disability involved? Very often those who would like to attend but can't still give according to their usual principle for giving.
2. There are people who hold full services in homes. This is as old as the New Testament itself. These give according to their established principles for giving. The rule of giving for some such fellowships is tithe-plus-overage, and for some it is strictly need-based, rejecting the tithe as an Old Covenant rule. This does not mean they give less, and in fact it can mean they give more, than ten percent. But the ten percent was a theocratic tax, given to support the sophisticated ecclesiastical structure of the Temple and priesthood, which was not replicated in the New Covenant, nor is the tithe reiterated as a requirement of New Covenant practice. As the house church has no major property expenses, all such funds can go to support full time ministry and other needs, or the minsters can be employed in "tent-making" and unpaid by the assembly, as with Paul, to further redirect money to real needs. local or global, as opposed to those operational costs that are created by a burdensome ecclesiastical infrastructure.
As for the question of whether attendance at a home or other building is necessary, it all depends on what is meant by necessary. Necessary to what purpose? Salvation? No, because salvation is secured by one thing, the death and resurrection of Christ, and our faith in Him.
However, there is often a point of confusion between Evangelicals and Catholics that pops up right here. When we say "not necessary to salvation," there is this recurring presumption that we evangelicals would treat the lack of requirement as an excuse not to do something. I think this is because the Roman model pictures all our actions as
contributing to salvation, whereas the evangelical sees our actions as
responsive to salvation, i.e., our actions confirm our salvation but do not contribute to it, because it is a finished work in Christ.
So right or wrong, based on what I've seen on this forum, it seems to be hard for our RC friends to accept that we would actually want to do something we didn't technically have to do to get or stay saved. Our incentive is purely love of Christ and the family relations of His body. The RC incentive is avoidance of doom. When we say we don't need to do something, to the purpose of avoiding doom, they do not appear to understand we would still do it anyway, because it is life and love and all that is good to us, that we would do it anyway, because it has become natural for us to do it.
So it is with the life of the local assembly. It is natural for Christians to love and be with other Christians. It is beneficial too, and we are under a New Covenant obligation to not forsake the assembling of ourselves together:
And let us consider one another in order to stir up love and good works, not forsaking the assembling of ourselves together, as is the manner of some, but exhorting one another, and so much the more as you see the Day approaching.
(Hebrews 10:24-25)
Note however the point of the assembly is not to secure salvation, but to stir up one another to love and good works. It's true he then warns them against giving up and reverting to their old ways. But such dire warnings are a normal part of the work of the Shepherd's staff, that blocks the sheep from error. And at the end he is confident they have the sort of faith that will endure the test of patience:
But we are not of those who draw back to perdition, but of those who believe to the saving of the soul.
(Hebrews 10:39)
So what then of those who permanently disassociate themselves from the lives of other believers? John accounts for this:
They went out from us, but they were not of us; for if they had been of us, they would have continued with us; but they went out that they might be made manifest, that none of them were of us.
(1 John 2:19)
Harsh, John. But true. The body of Christ is an organic being. It has a living unity through the shared experience of the indwelling Holy Spirit. No true believer is so remote they cannot be reached by God's Spirit. And God will not give His faithful commands with which they cannot comply, as that would impugn the rationality and goodness of God. So then every believer will always be able to find the fellowship of love to which they are driven, both by love and by requirement. Yet not a requirement of salvation, because that work is already done in Christ.
Peace,
SR