There are people who believe in God. Some believe in gods. Some believe in neither. Some say it is beyond human beings to be able to conclude ever whether God exists or not. This simple monotheist-polytheist-atheist-agnostic classification is as simple as Western philosophy (after the end of the era of Greek thinkers) generally tends to be. The differentiation becomes complicated in India whose philosophy says that to be an atheist is akin to not believing in oneself -- God or no God.
Leave aside theology, in simple English, what do you mean when you say, "My spirit is high"?
There is another school of thought that says whether God exists or not is a secondary question. There is no harm in trying to be one! Now, this should not be construed as super-ego. The philosophy simply means that when you consider yourself of yesterday, yourself of today and yourself of tomorrow, you see a tremendous process of evolution -- mental evolution especially. For one, you know and can do a whole lot of things today that you couldn't accomplish yesterday. Tomorrow you shall be all the more ‘abled’. This is a progress towards God, or that entity's attributes as believers describe them.
How do theists describe God? All-knowing. So try to know all. He is always in a uniform mood without mental upheavals and depression irrespective of the ever-changing situations. Try to emulate that feat too. Here you have two options -- the Buddha way of renunciation kind and the Krishna way of mythical kind. The second is a tall order. If you are a Buddha, you are with no one in this world; so feeling detached from everyone is easy. But if you are a Krishna, you are a son, a lover, a friend, a husband, a father... everything. Yet you feel none of the individuals related to you deserves a special treatment.
To be a Buddha would mean that, say, you wanted to be the king of the world. One day you indeed became the king of the world; yet you felt no sense of accomplishment or pleasure at that moment.
To be a Krishna would mean that there is somebody you love the most in this world -- one of your parents, your lover, your child… anyone. One day that person dies or departs from you forever. Yet you feel no sense of grief or remorse. It’s just a usual day. You go to school/ office, watch TV, go to play in the park/ club in the neighbourhood, maybe call your friends to dinner, and go to bed in the night as if nothing happened!
It’s extremely difficult for an individual to be spiritual by being a Krishna. But it’s not impossible. Several people have achieved this feat. They look common people like you and me; they are among our peers, moving about incognito. It is reported that when the news came on board that the Titanic was about to sink, out of the men who were to be evacuated at last (women and children were sent off on boats the first) some people died of panic. Many died in the fruitless stampede that followed. Some kept their cool. A few of the last kind survived. None of the other kinds did. That’s the incentive of keeping your SPIRIT high -- that's spirituality.
Next comes the question of the right candidacy. Everyone cannot be spiritual though whoever chooses to be religious can be so. In fact, the percentage of escapists, opportunists and rogue elements abound far more among religious people than they do among the spiritual. Indeed, in the era when dacoity was a major social phenomenon in Indian villages, most dacoits were devotees of Kali. Even today, the most unscrupulous of baniyas (I’m not referring to any caste but the Indian business class) start their day of cheating and fraudulence after a mandatory puja right after opening their shops.
There is but a problem with the yesterday-today-tomorrow conundrum. What I am today can be a god to what I was yesterday and what I will be tomorrow can be a god to what I am today. But my today may not necessarily be a god to your yesterday because we all evolve differently.
However, spirituality does not ask you to excel with a sense of competition. The competition is with the self. Strive, strive and keep striving till you perish. A man in his journey towards God passes many milestones in each of which he is a god in his own merit. As history (collective human experience that has been documented so far) suggests, no human being seems a possible contender to become God one day in future.
That is what makes us humble. That humility makes some believe there should be something that nothing could ever be -- they are the theists. It makes some others see existence as a phenomenon for the heck of it -- they are the atheists. Yet other people say both are speculating due to lack of sufficient information -- they are the agnostics. And finally, there are people who find this argument a wasteful indulgence. If God were to exist, He would be happier with subscribers to godliness instead of subscribers to rituals. If God were not to exist, at least you would be happy with yourself for being more honest than the follower of Allah in the Al Qaeda fold and the devotee of Ganesha and Lakshmi -- the unethical Marwari in your neighbourhood.