Euph:
I can see what you're getting at, too, but I agree with Didier that we're a fair way off being able to define the word that way. I would ask, though, why would unbelievers desire to claim the words "spirit" and "spiritual" when there are so many others that can describe the emotions that they feel are on a par with those of the believer?
Just to fully quote Alan's references:
SpiritualFunction: adjective
Etymology: Middle English, from Middle French & Late Latin; Middle French spirituel, from Late Latin spiritualis, from Latin, of breathing, of wind, from spiritus
1 : of, relating to, consisting of, or affecting the spirit : INCORPOREAL <man's spiritual needs>
2 a : of or relating to sacred matters <spiritual songs> b : ecclesiastical rather than lay or temporal <spiritual authority> <lords spiritual>
3 : concerned with religious values
4 : related or joined in spirit <our spiritual home> <his spiritual heir>
5 a : of or relating to supernatural beings or phenomena b : of, relating to, or involving spiritualism : SPIRITUALISTIC
- spir·i·tu·al·ly adverb
- spir·i·tu·al·ness noun
SpiritFunction: noun
Etymology: Middle English, from Old French or Latin; Old French, from Latin spiritus, literally, breath, from spirare to blow, breathe
1 : an animating or vital principle held to give life to physical organisms
2 : a supernatural being or essence: as a capitalized : HOLY SPIRIT b : SOUL 2a c : an often malevolent being that is bodiless but can become visible; specifically : GHOST 2 d : a malevolent being that enters and possesses a human being
3 : temper or disposition of mind or outlook especially when vigorous or animated <in high spirits>
4 : the immaterial intelligent or sentient part of a person
5 a : the activating or essential principle influencing a person <acted in a spirit of helpfulness> b : an inclination, impulse, or tendency of a specified kind : MOOD
6 a : a special attitude or frame of mind <the money-making spirit was for a time driven back -- J. A. Froude> b : the feeling, quality, or disposition characterizing something <undertaken in a spirit of fun>
7 : a lively or brisk quality in a person or a person's actions
8 : a person having a character or disposition of a specified nature
9 : a mental disposition characterized by firmness or assertiveness <denied the charge with spirit>
10 a : DISTILLATE 1: as (1) : the liquid containing ethyl alcohol and water that is distilled from an alcoholic liquid or mash -- often used in plural (2) : any of various volatile liquids obtained by distillation or cracking (as of petroleum, shale, or wood) -- often used in plural b : a usually volatile organic solvent (as an alcohol, ester, or hydrocarbon)
11 a : prevailing tone or tendency <spirit of the age> b : general intent or real meaning <spirit of the law>
12 : an alcoholic solution of a volatile substance <spirit of camphor>
13 : enthusiastic loyalty <school spirit>
14 capitalized, Christian Science : GOD 1b
synonym see COURAGE