Ancestor worship is humanity's most ancient and oldest traditional practice. Humanity has been honoring their dead ever since the first man and woman wondered what happens after death. In fact, the caring for the dead is one of the significant factors that distinguish human being from animals. Although animals do grieve for their dead, animals lack the mental capabilities of caring for their dead as human beings do. This is why human beings are the only species on the planet that perform elaborate rituals wishing that their dead find peace in the hereafter.
It is for this reason every culture has some type of ritual practice in place assuring that their dead loved ones find peace in the hereafter because it is one of the features that makes us human. That being said, there is no right or wrong way to wish that your deceased loved ones rest in peace. This is the reason regardless of our culture and ethnicity, we all can identify with the various ways of honoring the dead rather it be a moment of silence, the setting a deceased body aflame, the setting a light out to sea, etc. Without even having a full understanding of another's cultural beliefs. The is due to the fact that the ritual transcends logical thinking because we all have one thing in common and that is that we will all eventually face Death.
So, when the first human beings died, their loved ones were at a loss because they had never encountered death. All they knew was that there was a great emptiness and sorrow that they felt. Every culture around the world experienced this same loss when they first encountered death and described pretty much in the same way how they coped with this strong and painful emotional that they felt. Many cultures, including the Kamitic culture explain that the early human beings not understanding how to clearly express the sorrow they felt in death and the desire in their heart for their loved ones to be a part of them, resulted to cannibalism. Understand that ritual cannibalism was humanity's desire to express that one's deceased loved one was a part of them. It was an extension of the hunting ritual in which a hunter consumed the heart of an animal to absorb its' prowess and strength. This is the origin of the Eucharist or Holy Communion, which is the most important religious ritual practice in Christianity.
Other cultures resulted in taking body parts of their deceased loved ones, properly known as relics. To this day, there are a number of relics possessed by the Roman Catholic Church. Again, as bizarre and macabre as this may sound, the whole purpose of this ritual is to cope and subdue the overwhelming emotion of loss caused by death.
The reason these various rituals dealing with death came into existence in the first place is because our subconscious you will recall is the most logical part of our being and its purpose is to help us to physically survive based upon our beliefs. Since death is a natural phenomenon that we will all experience but there is no logical explanation as to why we die. Our subconscious, which processes everything that we experience like a logical computer, would have concluded that since there is no explanation as to why we die, there is no real explanation as to why we should live. Therefore, when early humans consumed part of the remains of their deceased loved ones or took a relic (body part of the dead), they in essence was trying to impress upon their subconscious a higher purpose of living rather it be to provide sustenance or to continue to provide life, to the community, as the meat of an animal did.
So the main purpose of honoring one's ancestors is to remember the sacrifices that those who lived before you made. If you do not remember the sacrifices that were made, then you will live your life based upon the erroneous belief that you and you alone are responsible for your evolution and survival. Not only that, you are not reminded of the purpose of living or inspired to live for a higher purpose such as to improve the quality of life for your loved ones or humanity overall. It should now become clear why Osar (Asar, Ausar, Osiris in Greek) was considered the most important ancestor or Lord of the Dead in the Kamitic tradition, and why Jesus is considered the Lord of the Dead in Christianity. You will also find this same reference in other cultures such Buddha the Lord in Buddha, Yama in Asian mythologies and so on. By the way, this is the reason every culture has a day to honor the dead rather it be Memorial Day, Hungry Ghost Day, Day of the Dead, etc.
Now, some cultures like the Africans and many of their descendants, many Asian and Latin Americans take the remembering of the dead a step further because they understand the psychology behind the practice. It is in their celebration of death, that you see from a reverse psychological perspective the beauty of life and vice versa.
They know that by honoring the dead on a monthly, weekly or even daily basis, one is able to inspire ethical and moral behavior among the populace.
This is because since we all will physically die one day, most of us do not fear death. We have been comforted by the belief that our soul will continue to exist after death, so we do not fear death. We do however fear how we will die. Will we die peacefully in our sleep or painfully kicking and fighting as we are dragged off to the other side?
So, many Africans and Asians continued to explore upon the concept of death in an effort to relieve us of the burdensome question of how to secure a glorious afterlife. It was discovered for some that they need to honor their dead every day, while others only needed to honor their ancestors once a month or a year. In some cultures, honoring the ancestors was the responsibility of the head of the household usually the men (or the eldest son) since traditionally it was the men who maintained law and order. In other cultures, it was the responsibility of gifted men, gifted or barren women, who viewed as shamans, because of their responsibility to guide the tribal community. All of which, later developed into a cultural practice, which is the reason there is no right or wrong way to honor one's ancestors and one does not need to belong to a particular religion to honor his or her ancestors. Honoring one's ancestors is a human spiritual tradition.
The cultural practice that developed was to put one's mind at ease by ensuring that their ancestor was at peace if they sense were not forgotten, remembered for his or her honorable deeds, and believed to continue to be a vital member of the community. Hence the rituals that developed from this understanding, was the offering food and drink to the ancestors, burning money for their ancestors so that they will enjoy their afterlife, and so on.
For the same reason, those who honor their ancestors, altars reflect what they believe the afterlife will be for their deceased loved ones and them in return. Many Asian ancestor altars like African and African descendant altars are usually either close to the floor or mid - ranged level, consisting of foods and other gifts that the dead will enjoy. My own altar is a reflection of my Kamitic and Kongo inspired beliefs, indicating that when I physically die my soul will return to the house or village where all my deceased loved ones dwell. I will be able to see my grandparents, great uncles and aunts whom I briefly met in life.
As you can see, this is a non-Western cultural thought, which is not taught but developed as a result of honoring the dead. In addition to this, many believe that if the ancestors are well taking care of they will in return assist the living. This simply means that the ancestors will relieve them of the emotional pain - particularly fear - brought upon them by death. In other words, after honoring one's ancestors one should be happy or feel at peace, because in the process or remembering one's ancestors, they are being reminded that they are spiritual being that is having a physical experience. And, in the end, because they honor the living memories of those who died before them, they will have a glorious afterlife as well. This is the reason most people who honor their ancestors do not fear death. Many will attest that they are more courageous because they feel that their ancestors protect and guide them from danger. The general belief or explanation is said to be that the ancestors continue to have an interest in the life of the living.
So, if you do not honor your ancestors or are simply honoring your ancestors out of tradition with no real explanation as to why you are engaged in the practice, you are not addressing the basic question regarding humanity, which is "What happens after death?" With no clear and practical explanation as to what happens after death, you will not have any purpose or reason to live. You will feel as if your purpose is to simply exist at the whims of the forces of nature or even God. With no purpose, you are not only, not fulfilling your destiny but on a course to eventually self-destruct because your subconscious mind, whose purpose is to physically survive.