A creed is a short statement of fundamental things. Sometimes the creed is very short (like the Muslim creed) and sometimes a big longer, for example, the Nicene Creed of the Christians.
This is my creed:
I believe that the power of the human mind can explain everything that has happened after the universe began. I believe that we can explain the universe by rules which do not change arbitrarily, and I do not believe there are forces or entities above nature which have the power to modify these rules. I believe that there has never been a reliable observation that proves the existence of a supernatural power.
I believe that an observation is only reliable when it can be repeated and observed by independent people. I believe that an explanation which can make a prediction confirmed by a reliable observation is truth. I believe that if there are two explanation for an observation, the preferred observation is the one which has less assumptions about unknown factors. I believe that things which are held to be true may be proven to be untrue by later observations.
I believe that life after death is impossible because the human mind is a material organ existing only in the observable universe, and that entropy explains that brain death is irreversible. The essense of human existence is at the very least our memories and senses. Our senses, such as vision, are clearly material (they exist in the human body). Our memory is a vast database of information stored in the cells of our brain. Since neither of these disappear into thin air after death, the concept of life after death is contrary to rational thought and observed facts.
I believe that people can collectively decide what is right and what is wrong. I do not believe that humans need the concept of eternal punishment or eternal reward to motivate decent behaviour.
I therefore do not believe that any human can speak with authority conferred by a god.