This is one of the favorite myths put forth by atheists and skeptics.
The fact is no formal historian would agree that the gospels contradict each other. They would say that there may be some disagreement on peripheral details between the gospel accounts, but the core facts are in clear agreement with each other.
For example, in 1912, when the Titanic sank, there were some people who said that it when on one end and broke in two before it went to the icy depths of the northern Atlantic. Other eyewitnesses were clear: No way! The ship when down in one piece. How could one group be wrong and the other right on a detail like that? No one knows, but the core fact remains: Titanic went down on its maiden voyage that night.
In a similar way, we can understand that the gospels agree on the core facts:
Jesus performed countless public miracles.
He was crucified under the order of Pontius Pilate.
He was buried in a tomb borrowed from Joseph of Arimathea.
He was raised on the third day after his crucifixion and appeared to many people.
It’s not a convincing or discrediting claim about the gospels to say they contradict each other, since the core facts are not in dispute. The resurrection claim, in particular, is the most extraordinary claim of the gospels and the witnesses of the New Testament do not disagree on this.