Raiders are not your typical temporary event, but a full-fledged part of the game. As well as not just an opportunity to rob someone and get more loot, by doing so, you should be prepared for other players to visit you too. We think this is hardly the news to anyone.
Recently added quests give you the opportunity to prepare for a raid, collect some weapons, axes, stock up resources to rebuild your base, etc. Just a usual routine, not some mission impossible, you know. If you are new to Last Day on Earth and quests seem difficult to you, then, well, it's probably a liiiitle bit early for you to go to raids.

To summon the raiders, your character must be at level 150.