This world is a very complex place. In spite of this complexity, there is one thing that everything has in common; everything has an opposite.
This is a world of duality. This means that nothing in it exists, without it's opposite. There is no cause, without effect; no light without dark; no good, without bad. There is no spiritual, without animal; no giving, without taking; no hardness, without softness; no love without hate; and no grace without sin.
The reason for this duality is that this is a spiritual-material universe. Everything in this universe is composed of a mixture of Spirit (energy), and matter. Einstein proved with relativity that all matter is actually energy in a condensed, or stepped down form, so everything is Spirit in either a higher, or a lower vibration rate. The higher the vibration rate of the substance, the more we will perceive that to be energy, and the lower the vibration rate, the more we will perceive it to be matter. This perception is based on our relative view point of the substance.
The two different natures of spirit account for the duality found in this world. The spirit of higher vibration is positive in nature, and the lower vibration is negative. Both are essential for the physical universe to exist. Do not make the mistake of equating positive with good, and negative with evil, because they are actually the same; and arise from the same source. In order to have a physical world you need a denser vibration level of spirit in order to have "solid" objects. All of these "solid" objects, are animated, or manifested by higher vibration spirit (i.e. The Holy Ghost, The Holy Spirit, The Eck, The Word, etc.).
There are many names for this higher vibration spirit, and each religion has their own name for it. In the same manner each religion has a different name for the originator of this power (i.e. God, Allah, Sugmad, Jehovah, etc.).
This is the true explanation of the holy trinity as taught by most of the world's religions. There is The Father (God). Out of The Father emanates The Holy Spirit. The Holy Spirit manifests The Son (mankind). The Holy Spirit manifests not only mankind, but everything in this physical universe. This is the secret to the "oneness of everything" as expressed by the mystics, Saints, and Saviors.
This world was created by God as a training ground for It's Son (Man). Man must learn through many lifetimes, how to navigate and understand the duality of this world, and to stay in balance with the positive, and the negative.
In spite of the duality of this world, there is one thing that all opposites have in common...God.