A pious person believes in something greater than themselves. Weather that is a deity, a specific way of living, or a noble goal it matters not. While Piety is often understood as the constant devotion to a deity, this is not a persons only venue to being pious. Let's look at the words "high ideal". Now in the first sense gods and goddesses represent our highest ideal of the spirit. We strive through ritual, through worship, and through imitation to reach the sides of our gods, to be like them. The idea here is that as spiritual beings having a human experience we need to nurture the connection our spirit has to the divine, in whatever form we believe that to be.
The next "high ideal" could be achieved by choosing a specific way of living our lives. This may or may not coincide with devotion to the gods. People who choose to live "green" lives devote themselves to conservation of the planet and a healthier more natural way to live. They humble themselves before their ideal of the right life every single day. Their devotion becomes their sustenance and they are pious to their high ideal.
The third act of Piety can be achieved by having and journeying towards a noble goal. A noble goal is one in which we believe that by attaining it we will have served others and become a better person because of it. A great example of this is the Peace Corps. When someone joins the Peace Corps they are setting themselves on the noble path of service and devoting their time and energy to helping others. This humble devotion to service enriches their lives and they become pious in their cause.
Piety is the pure state of our hearts. It is humble, it is selfless, and it hard yet rewarding work. One does not gain Piety by sitting around on their butt thinking, I love my god. One becomes pious by acting on their high ideals. You must do more than feel you must also move and take action. Only through active devotion and service can our heart, minds, and spirits lift us to a place of peace and love. If you believe in something so wonderful and great then don't go out proclaim it's greatness, just live it.
I will keep close to me my high ideals
I will act upon my noble goals
I will devote my live to the service of others
I will serve my gods by my actions