I don't know.... We need a lot more warm and fuzzy relationships in this troubled world. Right now we could use a lot of warm and fuzzy relationships between Muslims and Christians and Muslims and Jews. The attack in NYC yesterday reminds of all of that.
Having a degree and form of ideological unity with others is simply not what Scripture is talking about as regards Christian unity and "fellowship of the Spirit."
On one level I see your point, but on another level I do not. It is true that one should be true to one's conscience and convictions. However, that that not preclude the possibility and need to extend a hand of friendship to Christians of another faith and for that matter to non-Christians as well.
Extend a hand of friendship should include even atheists in compassion and grace, but that still is not Christian unity and "fellowship of the Spirit" which can only be realized among those who were and are manifestly born again, and thus to, in your words,
to accept one another as brothers and sisters in Christ. When were you born again?
After all, only God can judge. None of us know how many Evangelicals or Mainline Protestants or Orthodox or Catholics are presently in a state of grace and headed to salvation and how many are not. Certainly there are members in each group headed to Heaven and some that are not.
Rather, you can judge based upon Scripture, which noble seekers even subjected the veracity of the apostles to, (Acts 17:11) as well as by the reaction of souls to the Truth of Scripture. I am not talking about peripheral issues but believing the most basic Truths in heart. See further on.
As one raised devout RC, and who was told and treated as if I was a Christian since I was sprinkled and professed the Catholic faith (and confirmed) then I, but who became born again via heartfelt tearful repentance and evangelical faith in the Lord Jesus to save me on His account, then I can attest to the profound difference btwn the former and the latter, with its radical basic changes in heart and life. Even nature seemed new to me. Not that I always think or walk according to what I am in Christ.
Why not leave it up to God to decide which faith is best.
What? Do you really think the basic differences are not clear, and their Scriptural warrant or lack thereof? Do you really think the NT church (or any true believer) was praying to created beings in Heaven, and teaching one must become perfect in character in order to enter Heaven , or
other Catholic distinctives? Do you think they would be pro-choice, prosodomite liberals like the many liberal Caths and Prots?
All of us still proclaim Jesus.
So do Mormons, but whose Christ is a brother to Lucifer with an ascended (as man once was) human for a Father. Nor is the Biblical Christ one who made Mary the omnipotent dispenser of all grace. Among
many other examples of thinking of mortals far "above that which is written." (1Co. 4:6) Multitudes of souls who were later manifestly converted via Biblical repentant faith religiously professed Jesus before that, and for many or most professed Christians today, proclaiming Jesus typically basically to perfunctory professions in church.
All of us still believe in Baptism.
And which act itself (with proper form and matter) Catholics are told effects regeneration, even though in most cases the subject cannot obey the Biblical requirements of wholehearted repentant faith. Thank God some later truly personally come to such faith as damned and destitute sinners, and have a Biblical "day of salvation, and are rescued from their deluded state.
And many Catholics deny that "one baptism for the forgiveness of sins" in the Nicene Creed can be correctly interpreted as baptism being a matter of obedience versus normally being a requirement for regeneration.
And many Caths will disallow that holy, catholic and apostolic Church refers to the universal church of the Lord Jesus Christ and not necessarily or exclusively to any particular visible denomination, institution, or doctrine, as per the CF
SoF.
The vast majority of us still accept the Nicene Creed.
That professed assent to the Nicene Creed surely means that such is a Christian is absurd, as evidenced by what often passes for that in Christian threads here. One such professor told me the story of Abraham was likely a myth, and another (this week) that he never sins, that born again believers never do, even though they may trespass against others.
While the Nicene Creed affirms many facts souls can profess, it does not teach and preach why one so desperately needs salvation, apart from the simply statement of Christ coming to judge the living and the dead, and of being born again, and on what basis one may obtain salvation, nor make clear what the God-inspired substantive standard for faith and obedience is.
Since it seems that visible unity is currently not possible between any of the major groups, if we can at least achieve some brotherly love between us, then we will have achieved a measure of Jesus' wish that we all be one.
Division because of differences on basic Truths is better than unity at the expense of it, and while grace is to be shown (as well as reproofs as sometimes warranted) overall, there can no mutual brotherly love when one is not a brother.
But as then he that was born after the flesh persecuted him that was born after the Spirit, even so it is now. (Galatians 4:29)
Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?...And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people. Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you, And will be a Father unto you, and ye shall be my sons and daughters, saith the Lord Almighty. (2 Corinthians 6:14,16-18)