After taking a complete ride on the Ship of Death, your character will be under Divine Protection. This means that though you will be subject to damage from attack, you will be resurrected instantly, at no experience loss to yourself when slain - the Gods do not wish to see anybody unfairly victimised or slain over and over again by some sadistic enemy. Bear in mind though that you will gain no experience through combat, or watching combat while protected, either. Poisons of all kinds are also neutralised by protection (even those whose adverse effects are used as some beneficial defence like dynallca for deafness).
Divine protection, you should also know, is invalidated the moment you commit an offensive or potentially offensive move. Thus you must remain entirely pacifist and somewhat passive to retain protection. Protection is very important and very helpful, particularly when you are young - make use of it when you need it. Those of the level of Ordainable do not gain divine protection, and all characters are stripped of divine protection every New Years Day (1st of Midwinter).
Divine protection should not be confused with the resurrection aura, which you gain after a ride and resurrection from the ship of the dead. Resurrection aura is detailed in HELP SHIPAURA and is more robust but less absolute than divine protection.
While in Avalon, you can type PROTECTED to see a list of players on the game at any given time who are under divine protection; they are not worth attacking. If you wish to give up your protection, you may do so by typing RETRACT PROTECTION. Bear in mind that while protected, it is a gift you should not abuse and there are various safeguards against such ill-mannered actions as the attempt to horde puzzle or quest items in one's protected inventory, or idle hidden while retaining quest items so others may not reach them. Doubtless these safeguards will become obvious if divine protection or safe locations are used for such purposes.