Bible contradictions are often minute, insignificant details that only the most pedantic unbeliever picks up on in an attempt to cast doubt on the authenticity of the Bible. One example is the colour of the robe Jesus' tormentors put on Him just before His crucifixion. Was it purple, or was it scarlet?
There are many ways to explain this "contradiction", the first of which is that not all clothing is monotone. As I originally wrote this article, I was not wearing a plain shirt. It can be described as dark blue, purple or orange. This is because it has a fiery deer on it, and the fiery effect spreads across the whole shirt. It's not likely Jesus' robe had an image on it, but there's no reason to believe it couldn't have been legitimately described as two or more different colours at once.
But another possibility became especially obvious in 2015, when a single dress shook the internet. What colour was this dress? People argued about it for weeks, and even today it occasionally resurfaces. The dress appeared different colours to different people because of the way we perceive colour. In different lighting scenarios, colour appears very different. If, for example, you made your iPhone screen totally white, then placed it in front of a very bright light, the screen would actually appear to be black.
Because lighting affects our vision, it is entirely possible for Matthew and Mark to describe Jesus' robes as different colours because they saw, or spoke to different witnesses who saw different colours, for exactly the same reason I saw a blue dress with gold lining, but others saw a white dress.
But if the Bible is inspired by God, and is inerrant, why doesn't He tell us exactly what colours it was? He did. Because our perception of colour is based on lighting, so is our description of it. Thus, when the Holy Spirit brings a colour to the Apostles' memories (John 14:26), it is 100% accurate for them to describe it as they saw it. In allowing two different apostles to describe the robe as two different colours, God is actually ruling out the possibility of collaboration. The apostles didn't gather together to get their story straight, they wrote about what they remembered, or gathered from other witnesses. Therefore, we know the Bible is a historical record, not a creative forgery. The description of Jesus' crucifixion is from memory, not from imagination. In other words, as frequently happens with the Bible, that which was intended to disprove it serves as further evidence in its favour.