So I have been following this closely and I'm just going to say some things here that some people may or may not appreciate. Firstly let's start with who Christian is according to the Bible.
https://en.m.wikipedia.org/wiki/Apostles%27_Creed
The Apostles Creed is the admittance of God is Savior and Lord and truly God and his gospel testimony in its plain simplicity. It also is highlighting the importance of God's Church. The Holy Catholic Church it says. Catholic merely means Universal. So God In His Infinite Wisdom has instituted the Universal Church as the communion of Believers across the Spectrum. If anybody believes these things to be true generally speaking they will be Christian. This is a very Broad and simplistic confession.
There are some notable things that are missing from this Creed. The big one is the nature of God in three persons. This is remedied in the next confession.
https://www.crcna.org/welcome/belief...s/nicene-creed
This Creed is a little different in that it explains the nature of God the Father God the son and God the Holy Spirit as God from God, not being created but rather preexisting. But it doesn't quite spell it out.
http://www.reformed.org/documents/index.html
The anastasian Creed is clear and concise. Any man who disagrees with these is in the deception of the devil and believing a lie.
The Christians are trinitarian, believing in God is three persons separate and Jesus Christ is one person. Jesus Christ was born of a virgin died for our sins and it through him we receive forgiveness and him alone.
Ask for anybody claiming to have an authority on Truth the only truth is the truth that Jesus Christ proclaimed, and as he said so himself he is a fulfillment of the law and Prophets. He is the Messiah that was promised in the Old Testament and witnessed by the books we now know in the Old Testament., the New Testament is the history of the Apostles Ministry and their confessions and thoughts, and are the inspired word of God. The 66 books of the Protestant Bible are held to be 100% inerrant, divinely given.
No such people who believe in Jesus and the Bible can be called christless. This is in no way Bible worship or false piety that we have confessions and creates that are based solidly in scripture and we believe the words of God's Own truth. Anybody who says otherwise himself is a heretic. Anybody who claims do you have a very specific Church or view of scripture not held by the majority of other Christians is himself a heretic. Anybody who claims to have a special Revelation from God that is not in accordance with scripture or 6 to add or remove from spiritual truth of the Bible, that was given to them and them alone is himself a heretic.
Furthermore any persons who look at the plain truth of scripture and it's clear unambiguous meanings and reject the truth for a lie are Heretics. There are people who believe in things that are not quite biblical and these beliefs are called heterodox. It is possible to believe in heterodoxy rather than Orthodoxy which is the mainstream accepted forms of belief of the Bible and its interpretation. anybody who reject God's truth for selfish reasons in plain rebellion of scripture is a heretic.