Lets take that God does not exist, and was only created to give moral values more importance and respect for the given rules of The ten commandments for example. Also quite possibly, taking humans nature, idea of guilt, being observed and punished for breaking the rules is quite an intelligent basic idea to be used in order to keep the idea respectable and well remembered, to have the rules kept. Rules bring idea of safety and protection as well as higher purpose than keeping basic instincts satisfied. Creating a holly importance to ideas like love, respect, loyalty, peace, trust, faith and hope have brought these ideas significant importance and higher purpose of life.
Quite simply, they keep world's peace and harmony making humanity a way forward to keep the human kind living with each other in peace and mutual respect.
So yes, it is helpful that religion has been invented and given a name but that is also what makes it also questionable to be a metaphysical it seems to be simply a humans invention. What also makes the concept of God's existence questionable is what history shows...
Wars for many countries' independence and land, world wars, Holocaust, Vietnam War, 9/11 bombing, terrorism... and so many more other human tragedies that were pure evil, now, if God as he or she is described would these tragedies have happened? Some would say that we are all part of God's plan and will be all punished or rewarded in afterlife, and if one suffers, innocently, the place in heaven will be prepared for him or her. All that, comforting enough for some, is enough to justify cruelty and hate amongst people. For some it is enough to have a hope for happiness in life after life for eternity when we are no more than metaphysical soul, yes, foe some this gives a reason for a belief in higher purpose of life being happiness after death... What a life that is someone would ask, well catholics believe that suffering can be a blessing, and suffering and sacrifice is an enormous part of humans life. Polish people have even this saying, after being through two wars, invaded, murdered and robbed country in Europe, one of the famous polish writers calls Poland, "The Christ of the nations" as its people are bound to suffer considerable amount before the nation will rise and become happy and blessed.
Among catholics, it is believed that who believes in God, father of Jesus Christ, is given strength and comfort of being looked after taking risks and going through difficulties of life taking them as parts of God's plan, forgiving and never wanting a revenge for bad things that happen in life... And those who don't believe in his existence are band to be doomed and have a weakness and lower aim of life.
Now, let's take that God as a higher power overlooking the good rules and morals in humans' life, had never been invented, would men be equally determined and strong in believing in doing good and higher purpose in life than satisfying basic human instincts. Would they manage to protect moral values and mutual respect among men knowing that the only award for it is good relationship with people and if we steal something from someone there will be no feeling of guilt or punishment for breaking moral values; and that the punishment would be going to prison and then getting out and then why not doing it again.
Would believing in ourselves and our own equally good values and keeping them as important and making life meaningful be the same as believing in higher power that would give strength to keep the importance of the values. The values that would equal the Ten Commandments, or Decalogue, "a list of religious and moral imperatives that, according to the Hebrew Bible, were spoken by God to the people of Israel from the mountain referred to as Mount Sinai or Horeb, and later authored by God and given to or written by Moses in the form of two stone tablets. They are recognized as a moral foundation in Judaism and Christianity, and their substance also figures in Islam."(Ref.2)
The phrase "Ten Commandments" is generally used to refer to similar passages in Exodus and Deuteronomy The passages in Exodus 20 and Deuteronomy 5, traditionally divided into fourteen or fifteen verses, are each identified in the biblical text as containing ten elements. These passages declare the Lord, who brought the Israelites out of slavery in Egypt, to be their God; prohibit worship of other gods before the Lord, and the making or worshiping idols; threaten punishment for those who reject the Lord and promise love for those who love him; forbid misuse of the Lord's name; mandate observance of the Sabbath and honoring one's parents; and finally prohibit murder, adultery, theft, false testimony, and coveting of one's neighbor's goods. Various religions and denominations translate and interpret the Commandments in different ways." (Ref.2)
If we didn't say that these ten commandments were given from God but created by a wise and thoughtful person who believed that people would interpret the commandments for a benefit of human kind.
1. "prohibit worship of other gods before the Lord" -could be translated into believing that these ideas are rightful,
"the making or worshiping idols" - inventing of other values like for example, opposite ones, evil ones would be a bad thing,
"threaten punishment for those who reject the Lord and promise love for those who love him" - punish ones who break the values, these who steel, kill etc
(* all above count into the first commandment in catholic interpretation of the Bible)
2. "forbid misuse of the Lord's name" - would be quite metaphysical to add more mysticism to the idea
3. "mandate observance of the Sabbath" - cherish and respect saint days which would teach us respect for tradition and culture
4. "honoring one's parents" - quite a direct interpretation, showing respect for parents and love in family
5. "prohibit murder"
6. "prohibit adultery"
7." prohibit theft"
8. "prohibit false testimony"
9. * (not mentioned in here but it is included in the Catholic version of the ten commandments) - "prohibit desire for neighbor's wife"
10. and "prohibit coveting of one's neighbor's goods" - [5-10] - prohibit doing, saying or meaning any harm or hurtful intention to other person or yourself"
If we took this commandments as given by a wise philosopher would that be enough for human kind to obey these rules? Perhaps at the time when they were invented there was no other way to keep them respected but to say they are from God and if not obeyed, the punish will come?
What ever reason they were named to come from God if interpreted in this basic way I showed above they should only serve good and making life better creating overall respect for life and others. There is no doubt they are one of the greatest inventions of all. The question is was there really a need to name them to come from God? Would our humns' power, self believe and mutual respect be enough to make this values survive till these days or was it so well thought of one day thousands years ago with one man with name of Moses who decided that humans' strength is faulty and their nature is hesitantly questionable that it was safer for the human kind and more likely for them to survive with God looking over them and guarding these values.
References:
1. The Bible
2. http://en.wikipedia.org/wiki/The_ten_commandments
3. Paulo Coelho, I sat by the Piedra river and I cried (inspiration for the research and thoughts)