I am not a historian, but I have many friends who are. Two contemporaneous cross-references seems to be the agreed upon criterion.
I don't know who your friends are but my criteria is the official requirements that the historical method spell out. There are countless historical events taught in history classes in colleges around the world which do not have any contemporary sources what so ever. For example even everyday claims like the Gallic wars have zero contemporary accounts. The earliest sources that exist are 950 years after the originals and we only have tow copies, yet these wars appear in ever western civilization book printed. Just guess I would suggest more accepted facts from ancient history have less than 1 or a single source which is not contemporary than those that meet your criteria. You further compound the problem if you accept evolution and it's massively older and complete lack of contemporary witnesses. However just to have some fun I will accept your standards because unlike most of history the bible exceeds them.
It is generally believed that Matthew was written before A.D. 70 and as early as A.D. 50 - NOT CONTEMPORANEOUS.
It most certainly is contemporary. It does not matter what date the event was written down, it matters if the person existed at the same time, the bible goes further in that most Gospel writers were personal eyewitnesses to the events themselves. Virtually no event in human history was recorded real time is it occurred. I don't think that is even theoretically possible so no historical standard has ever existed that requires it. In history and law the only relevant issue is was the witness there. Exactly what event do you know of that has a real time recording of it before the invention of TV and radio. In fact even it has a delay and is not real time.
Generally, Mark is said to be the earliest gospel with an authorship of between A.D. 55 to A.D. 70. - NOT CONTEMPORANEOUS.
Do you know what the standard that can be reasonably expected for texts of this time. Not a single book of any kind can even come fractionally close to the bible for multiple attestation, time period between event and recording them in extant copies, and integrity of the textual tradition. Not one, there is not even a close second. Your friends are either sadly mistaken or they do not study ancient history.
John is the last of the gospels and appears to have been written in the 80's to 90's. Most scholars say it was written in the early 90's. - NOT CONTEMPORANEOUS.
Three strikes ... you're out!
You might call a fair ball that clears the fence a strike but the three points would still be counted by any actual historian or legal expert in testimony and evidence. Why don't we ask a few of the most relevant and famous scholars?
The noted scholar, Professor Edwin Gordon Selwyn, says: "The fact that Christ rose from the dead on the third day in full continuity of body and soul - that fact seems as secure as historical evidence can make it."
Many impartial students who have approached the resurrection of Chris with a judicial spirit have been compelled by the weight of the evidence to belief in the resurrection as a fact of history. An example may be taken from a letter written by Sir Edward Clarke, K. C. "As a lawyer I have made a prolonged study of the evidences for the events of the first Easter Day. To me the evidence is conclusive, and over and over again in the High Court I have secured the verdict on evidence not nearly so compelling. Inference follows on evidence, and a truthful witness is always artless and disdains effect. The Gospel evidence for the resurrection is of this class, and as a lawyer I accept it unreservedly as the testimony of truthful men to facts they were able to substantiate."
Professor Thomas Arnold, cited by Wilbur Smith, was for 14 years the famous headmaster of Rugby, author of a famous three-volume History of Rome, appointed to the char of Modern History at Oxford, and certainly a man well acquainted with the value of evidence in determining historical facts. This great scholar said: "The evidence for our LORD's life and death and resurrection may be, and often has been, shown to be satisfactory; it is good according to the common rules for distinguishing good evidence from bad. Thousands and tens of thousands of persons have gone through it piece by piece, as carefully as every judge summing up on a most important cause. I have myself done it many times over, not to persuade others but to satisfy myself. I have been used for many years to study the histories of other times, and to examine and weigh the evidence of those who have written about them, and I know of no one fact in the history of mankind which is proved by better and fuller evidence of every sort, to the understanding of a fair inquirer, than the great sign which GOD hath given us that Christ died and rose again from the dead."
Wilbur Smith writes of a great legal authority of the last century. He refers to John Singleton Copley, better known as Lord Lyndhurst (1772-1863), recognized as one of the greatest legal minds in British history, the Solicitor-General of the British government in 1819, attorney-general of Great Britain in 1824, three times High Chancellor of England, and elected in 1846, High Steward of the University of Cambridge, thus holding in one lifetime the highest offices which a judge in Great Britain could ever have conferred upon him.
"I know pretty well what evidence is; and I tell you, such evidence as that for the Resurrection has never broken down yet."
Simon Greenleaf (1783-1853) was the famous Royall Professor of Law at Harvard University, and succeeded Justice Joseph Story as the Dane Professor of Law in the same university, upon Story's death in 1846.
H. W. H Knott says of this great authority in jurisprudence: "To the efforts of Story and Greenleaf is to be ascribed the rise of the Harvard Law School to its eminent position among the legal schools of the United States."
Greenleaf produced a famous work entitled A Treatise on the Law of Evidence which "is still considered the greatest single authority on evidence in the entire literature of legal procedure."
In 1846, while still Professor of Law at Harvard, Greenleaf wrote a volume entitled An Examination of the Testimony of the Four Evangelists by the Rules of Evidence Administered in the Courts of Justice. In his classic work the author examines the value of the testimony of the apostles to the resurrection of Christ. The following are this brilliant jurist's critical observations:
The great truths which the apostles declared, were, that Christ had risen from the dead, and that only through repentance from sin, and faith in Him, could men hope for salvation. This doctrine they asserted with one voice, everywhere, not only under the greatest discouragements, but in the face of the most appalling errors that can be represented to the mind of man. Their master had recently perished as a malefactor, by the sentence of a public tribunal. His religion sought to overthrow the religions of the whole world. The laws of every country were against the teachings of His disciples. The interests and passions of all the rulers and great men in the world were against them. The fashion of the world was against them. Propagating this new faith, even in the most inoffensive and peaceful manner, they could expect nothing but contempt, opposition, reviling's, bitter persecutions, stripes, imprisonments, torments, and cruel deaths. Yet this faith they zealously did propagate; and all these miseries they endured undismayed, nay, rejoicing. As one after another was put to a miserable death, the survivors only prosecuted their work with increased vigor and resolution. The annals of military warfare afford scarcely an example of the like heroic constancy, patience, and unflinching courage. They had every possible motive to review carefully the grounds of their faith, and the evidences of the great facts and truths which they asserted; and these motives were pressed upon their attention with the most melancholy and terrific frequency. It was therefore impossible that they could have persisted in affirming the truths they have narrated, had not Jesus actually risen from the dead, and had they not known this fact as certainly as they knew any other fact. If it were morally possible for them to have been deceived in this matter, every human motive operated to lead them to discover and avow their error. To have persisted in so gross a falsehood, after it was known to them, was not only to encounter, for life, all the evils which man could inflict, from without, but to endure also the pangs of inward and conscious guilt; with no hope of future peace, no testimony of a good conscience, no expectation of honor or esteem among men, no hope of happiness in this life, or in the world to come.
"Such conduct in the apostles would moreover have been utterly irreconcilable with the fact that they possessed the ordinary constitution of our common nature. Yet their lives do show them to have been men like all others of our race; swayed by the same motives, animated by the same hopes, affected by the same joys, subdued by the same sorrows, agitated by the same fears, and subject to the same passions, temptations, and infirmities, as ourselves. And their writings show them to have been men of vigorous understandings. If then their testimony was not true, there was no possible motive for its fabrication."
Evidence That Demands a Verdict - Ch. 10 p. 2
Now besides these guys being far more familiar with what constitutes reliable texts, testimony, and historical evidence than me, you, or your friends, they had a lot to do with creating the standards, themselves.
if I replace Hosea with Mein Kampf, and God with Führer, would you notice a substantial disconnect?