My opinion is that the universal church does have a function on earth. And I disagree that the universal church is "man-made nonsense."
The concept of the universal church has its basis in scripture or else I would not believe in it. And it is far from a "useless" concept. All believers, no matter how isolated from other churches, are encouraged by the knowledge that they all are part of the body of Christ and share in its blessings — and sufferings — no matter how removed they are from other believers.
Evangelism is certainly a commandment, but it is not the only function of the local church or the universal church. We are to build up and comfort each other, bear each others' burdens and contend for "the faith that was once for all delivered to the saints." And in that, your belittled "creeds" play an important role.
You certainly have a right to your "opinion" but not a right to your own facts. The UIC theory has no Biblical basis. Indeed, it is anti-Biblical in nature and repudiates the Biblical concept of salvation at its most basic level.
Let me ask you a simple question, What is the most basic concept of the lost condition versus the most basic concept of the saved condition? Is the basic concept of either rooted in the day of Pentecost or in the fall of man in Genesis?
In case you don't understand exactly what I am getting at, let me further elaborate. What is your most basic definition of "death"? Is your most basic definition of death rooted in the day of Pentecost in Acts 2 or in Genesis 2:17? What is the solution to your most basic definition of death?
In case you still don't see what I am trying to stir up in your mind, then let me ask you a further question. Who is the source of life, light and holiness and what role does "death" play in relationship to that source?
In case you still don't see what I am getting at, if "death" is "separation" (separaion spiritually, separation from physical substance; separation of whole man from God in Gehenna) and at its most basic level the whole concept of death originates with spiritual separation from God then what is the only solution to spiritual separation if not spiritual union? Finally, is spiritual separation being separated from God as life, light and holiness (Eph. 4:18). Can any fallen human being existing in spiritual separation from God, thus separated from the life, light and holiness of God have any kind of fellowship with God or please God? Once again is this a Genesis problem with a Pentecost solution or a Genesis problem with a Genesis solution obtained by promise? Is being "created in Christ" a Pentecost solution or a Genesis solution for all those chosen "in him" before the foundation of the world (Eph. 1:4; Rom. 8:28-30).
Finally, let me sum up all my questions in one simple question: Has there ever been a time or place or person where salvation has been obtained OUTSIDE of Christ before or after Pentecost?
Your UIC theory demands that either regeneration (Eph. 2:10) or the baptism in the Spirit = is placement spiritually "in Christ" which did not occur until Pentecost. Hence, all fallen human beings prior to Pentecost were SPIRITUALLY OUTSIDE of Christ. Your
modus operandi for being "in Christ" is Pentecost coming of the Spirit, either defined as regeneration or baptism (or both) by the Spirit into the mystical body of Christ is it not? That doctrine repudiates the most basic rudiments of Biblical salvation for all Pre-Pentecost people, thus preaching another gospel, another savior, another way of salvation prior to Pentecost than after Pentecost but that is not the united testimony of scripture (Jn. 14:6, Acts 4:12; 10:43; 26:22-23; heb. 4:2; etc.).