If I read you right I have to say I agree to all that. Except for the part "within the church establishment itself" Whatever "church" the antichrist is a part of will have nothing to do with the church of God. Pretty much as Catholicism is being totally absorbed into mankind and is losing any visible features of godliness so also will this syndicate be. That's why I'd call it a syndicate than a church.
The Falling Away from the faith, requires the Church establishment (leadership) as the City of Peace (Jerusalem), opening the way for the unveiling of the Sons of Perdition. The final act of betrayal will be by those who profess Christ, yet sell him out. The Act of replacing the Daily Sacrifice with the Abominations of Desolation is by the Establishment themselves, who have been infiltrated by the enemy (The TARES).
1A day of the Lord is coming, Spiritual Jerusalem (Where God Dwells Pentecost), when your possessions will be plundered and divided up within your very walls.
The Church denominations and Assemblies will be infiltrated by the Sons of Perdition (Progressive Liberals), advocating conformance with the world and man's experiences as truth, rather than the authority of Jesus and his objective moral laws.
2I will gather all the nations to Jerusalem (Church) to fight against it; the city (Christ's Church) will be captured, the houses (Assemblies) ransacked, and the women (Denominations) raped. Half of the city will go into exile, but the rest of the people will not be taken from the city.
3Then the Lord will go out and fight against those nations, as he fights on a day of battle.
The exiled gentile nations (TARES) who trample the outer unmeasured court, when the time of the fullness of the gentiles comes, when they will break the power of the Holy People (the Living Stones), will signal the end of the preaching of the gospel.
This is the climax to the end, where the Man (Anthropos) of Sin (Sons of Perdition) will dethrone Christ and to place something else (Abomination of Desolation) in his place, in conformance with all the world.