Why was Surat Al-Ikhlas given this name?

There are two reasons mentioned for naming Surat al-Ikhlas (Sincerity): The first is that it embodies sincerity to Allah Almighty, so the believing reciter of it becomes sincere. Or, because Allah Almighty chose it exclusively for Himself, and nothing is mentioned in it except His own specific news. Both reasons are correct and there is no contradiction between them. It was also said that whoever believes in it becomes sincere in Allah's religion, and whoever dies upon it will be saved from the Fire.