You've been a little heavy-handed with the shaker while making soup, and now you are faced with possibly serving a salt lick for your first course. While your guests may be polite and not mention it, you'll still know the soup is not right. Over-salting happens to the most experienced cooks, and usually you can make soup less salty, except in the most extreme cases.
Don't panic. Mistakes in the kitchen happen, and a level head will always prevail over a panicked one. Before you start dumping in other spices, trying to cover up the salt, take a second and breathe. Cleanse your palate and taste the soup again to get a true estimate of the degree of saltiness.
Peel and quarter one potato and drop it into the soup. Allow it to sit for 15 minutes, then remove it. This old-school method can take away a low degree of saltiness. The potato will absorb the salt. Take a bite of it once you've removed it to taste the difference.
Neutralise the salt with a little sugar or cider vinegar. Try a little at a time, about a teaspoon, until you've achieved the desired result.
Add more ingredients and liquid to the soup. This is the last resort, since you probably didn't want to make such a large amount of soup. By doubling your recipe, you are decreasing the ratio of salt to soup, which will make it less salty.
Do not try to cover up the salt with other spices. Salt is salt and cannot be masked with pepper, cumin, bay leaves, cinnamon or anything else. All you will be doing is making a bigger problem with unknown but likely disastrous results.