Be deaf when anyone speaks to you apart from Jesus Christ,
Who was of the stock of David,
Who was from Mary,
Who was truly born, ate and drank,
was truly persecuted under Pontius Pilate,
was truly crucified and died
in the sight of beings heavenly, earthly and under the earth,
Who also was truly raised from the dead,
His Father raising him.*
The style of these ancient words may be more familiar to some readers! I am focussing on the good advice in the first line, rather than the doctrine or dogma following it.
These slogans (creed-like phrases) were written by Ignatius of Antioch about 1,900 years ago. As we shall see, unsurprisingly Jesus had anticipated the problem. The false speaker was a problem from Jesus' own antiquity.
Ignatius came just after the Apostles. He was one of those seeking to ensure the scattered groups of Christians held to orthodox beliefs. (I do wonder about one clause there, Ignatius!) He was martyred in Rome about 110 CE.
Round about those times there were rival voices and even the emergence of rival/alternative/extra gospels. Strong leaders with alternative views gained followers and established belief communities. The complex overall situation in the century after the first Easter is obscure to me. Clearly, the spread of unorthodox teaching saw the emergence of contenders such as Ignatius. His admonition to listen only to those who speak through Jesus Christ is a telling one. (How, however, is that done?)
The debate over the fourfold Gospel (four, no more, no less) was probably beginning. Evidence comes from Irenaeus, disciple of Polycarp of Smyrna, who had been in Ephesus when the Apostle John lived there. Irenaeus was a missionary in the west (Gaul, a.k.a. France) (E. Britannica). It is overwhelmingly true today that the fourfold Gospel (Matthew; Mark; Luke; John) is securely established.
Beliefs? Credal formulas continued to be developed until the texts (creeds) known as 'Apostles' and 'Nicene' were adopted. Many Christian groups today profess adherence to the creeds. Some corporately recite the words from time to time. Sounds secure? Might have pleased Ignatius, Polycarp, et al.? Maybe, but, a couple of years ago (2013 I think) I heard a current day (employed) leader in a professing body asked in a radio interview about the extent of their commitment to the doctines regularly confessed. No real surprise but, I regret to say, the answer was that the professional's recitation of the creed was 'aspirational', rather than actual! So, the stated allegiance of a leader, or the identity of their salary paying body, or their formal label, unfortunately is no guarantee. Sadly, they may speak to you 'apart from Jesus Christ'. Difficult?
The only reliable test is specific comparison with the Gospels, the NT, the Bible. (Note, however, almost everyone claims Bible support.) You can and should check! Test everyone, including me! So Jesus had previously warned; John echoed him. Those truly informed by the Bible had resources to resist the blandishments of falsity. (This is largely a matter of knowing the whole, rather than a verse here or there.)
Matthew 7
True and False Prophets
15 “Watch out for false prophets. They come to you in sheep’s clothing, but inwardly they are ferocious wolves. 16 By their fruit you will recognize them. Do people pick grapes from thornbushes, or figs from thistles? 17 Likewise, every good tree bears good fruit, but a bad tree bears bad fruit. 18 A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit. 19 Every tree that does not bear good fruit is cut down and thrown into the fire. 20 Thus, by their fruit you will recognize them.True and False Disciples
21 “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but only the one who does the will of my Father who is in heaven. 22 Many will say to me on that day, ‘Lord, Lord, did we not prophesy in your name and in your name drive out demons and in your name perform many miracles?’ 23 Then I will tell them plainly, ‘I never knew you. Away from me, you evildoers!’I John 4
1Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world. 2 This is how you can recognize the Spirit of God: Every spirit that acknowledges that Jesus Christ has come in the flesh is from God, 3 but every spirit that does not acknowledge Jesus is not from God. This is the spirit of the antichrist, which you have heard is coming and even now is already in the world.
This is not the 'full story'. There is more (similar) in my page, 'Be Alert'.
Scripture quotations are taken from the Holy Bible, NEW INTERNATIONAL VERSION®, NIV® Copyright © 1973, 1978, 1984, 2011 by Biblica, Inc.® Used by permission. All rights reserved worldwide.
*Ignatius, Trall. 9:4, quoted in J.N.D.Kelly, Early Christian Creeds, 3rd Ed., (London; New York: Continuum, 2006) 68 (in Google Books)