Yes, the Apostles were visible human beings as was Christ as were other Christians as are we who continue in the same faith as Christ preached and the Apostles taught. Where I disagree is when any organized institution presumes to be that visible union alone in exclusion of all other assemblies that share in the Christian faith. Just as Paul reminds us that it is not who Apollos baptized, or Peter or Paul but who are joined together in that we are "like living stones, are being built into a spiritual house to be a holy priesthood" (I Peter 2:5) as the Holy Spirit inspired Peter to write.
This union that IS one in Christ is so not because of everyone being gathered together under one umbrella organization that bills itself as THE church of Christ, but as the one spiritual union, a spiritual "house" that makes us ALL part of the holy priesthood of all believers. Your magesterium has made moves recently to try to demonstrate this attitude of inclusion of the body of Christ and they FULLY accept that being a member of the Roman Catholic Church is NOT a prerequisite to being part of the redeemed in Christ. Do you disagree with them? Rather than take so much time trying to convince those of us who DO follow after Christ in faith and in holiness of life, why not worry more about those within your own congregation that wear the Catholic label but who do not evince that in their own lives? Why does it matter that someone is Baptist and not Roman Catholic if the faith is there as well as the evidence of that faith?
That they are damned because of their works, not earning salvation by them,or by the power of their church, (Rm. 3:10-23; 6:23; Acts 4:12) and are utterly destitute of any merit by which they may escape their just and eternal punishment in Hell-fire, and must therefore look for the mercy of God in Christ, trusting the risen Lord Jesus to save them by His sinless shed blood, by which faith they are counted righteous, a faith that is expressed in baptism and following Him, and enabling growth in grace toward perfection, “that the world may believe that thou hast sent me.” For the regenerate realize supernatural changes which correspond to Divine promises and that overall defy naturalistic explanations, including an essential “unity of the Spirit,” which, as those who have been born of Him and walk therein can attest, results in a spontaneous fellowship that transcends race and tongue, nations and locations, and
is greater than their differences, as all have a common Scripture-based conversion and relationship with the one Lord.
What the spiritual “oneness” of Jn. 17 cannot refer to is complete comprehensive doctrinal unity, except as a goal, which has never been realized.
What you will not see in the New Testament church is that of a separate class (and clothed) of sacerdotal clergy called “priests” (versus bishops/elders as one office), much less required (with rare exceptions) celibacy for them;
Or praying to the departed, and the hyper exaltation of and devotion to Mary above that which is written; (1Cor. 4:6)
Or that regeneration cannot precede baptism (as some hold), or baptism except to those who could fulfill the stated requirements of hearing, repentance and faith; (Acts 2:38; 8:36,37; cf. 8:12; 16:32-34; 19:4,5)
Or the Lord's supper being the means by which souls gain life in them, or that not “discerning the body” referred to the elements of the supper versus the church;
Or bowing down to icons, believers bowing down to any other believer, or an exalted supreme magistrate in Rome (versus warnings against such exaltation: Mt. 23:8; Jude 1:11; 3Jn. 3:9-11; Rv. 2:15) and to whom all the churches were directed to look to,
Nor assured perpetual formulaic magisterial infallibility as per Rome;
Or the mention of any successors to the original apostles (such James: Acts 12:2) besides Judas, he being elected to preserve the foundational twelve apostles, (Acts 1:16-26; cf. Rev. 21:14) and that by lots, preventing political maneuverings and things that resulted in extended papal absences (a headless Roman church), and men being chosen who were not even qualified to be church members, let alone successors to Peter.
Or a separate class of believers called “saints,” or the mention of the postmortem location of the saints being in purgatory versus with the Lord. (Lk. 24:43; 2Cor. 5:8; Phil. 1:23; 1Thes. 4:17)
Or any pastored Christian bodies being called anything less than a church if they preached the gospel by which men are regenerated, and thus baptized by the spirit into the church, (1Cor. 12:13), even when under a separatist pastor, (3Jn. 3:9-11) versus “ecclesia communities” (as Rome refers to evangelical churches as) because they do not subscribe to the unScriptural perpetuated Petrine papacy of Rome and all that which flows from it.
Or conversion being the result of intellectual indoctrination and the supremacy of the church in Rome, fostering faith in the church and one's merits for salvation, versus the aforementioned conviction by the Holy Spirit such as true preaching can effect, usually resulting in conversions in the same hour (though preparation can take a lifetime), and souls can be saved and spiritually added to the church anywhere, even being left alone in the desert, (Acts 8:26-39; cf. 1Cor. 12:13);
This being said, the kingdom is sadly divided on earth, partly due to necessity because faithfulness requires separation, (Mt. 10:34-36; 1Cor. 11:9) resulting in the Church consisting of churches which have their own magisteriums, keeping in principle the ordination of leadership, which is also seen in Catholicism, despite the elitist ecclesiology of Rome.
It would seem that if you believe Christ and the Apostles to be visible, than it should follow they were also an ORGANIZED and VISIBLE Church that would continue in succession though the ages. Scripture does not say the visible church would end with the Apostles,dear sister.
The only VISIBLE and ORGANIZED Christian Church that can be traced back to the time of the Apostles is Catholicism with its Sacramentalism given to us by Christ Himself
There are volumes upon volumes of writings from the early Church Fathers that back all this up and defend Catholicism through the ages.
As the late Bishop Sheen so beautifully stated....
"If you would find Christ today, then find the Church that does not get along with the world. Look for the Church that is hated by the world, as Christ was hated by the world. Look for the Church which is accused of being behind the times, as Our Lord was accused of being ignorant and never having learned. Look for the Church which men sneer at as socially inferior, as they sneered at Our Lord because He came from Nazareth. Look for the Church which is accused of having a devil, as Our Lord was accused of being possessed by Beelzebub, the Prince of Devils. Look for the Church which the world rejects because it claims it is infallible, as Pilate rejected Christ because he called Himself the Truth. Look for the Church which amid the confusion of conflicting opinions, its members love as they love Christ, and respect its voice as the very voice of its Founder, and the suspicion will grow, that if the Church is unpopular with the spirit of the world, then it is unworldly, and if it is unworldly, it is other-worldly. Since it is other-worldly, it is infinitely loved and infinitely hated as was Christ Himself. … the Catholic Church is the only Church existing today which goes back to the time of Christ. History is so very clear on this point, it is curious how many miss its obviousness…”