Religions have fulfilled an important evolutionary purpose in human history. Some people even claim that because of this we can never live without of them. However, even if having a religion really does give one an evolutionary advantage, nothing stops people from rejecting the current decidedly very old-fashioned world-religions and creating new and better ones.
Humans have created the existing religions to serve the needs of their society and to fulfill some personal needs. Humans can also create new, modern religions to serve the modern societies with a new and extremely different set of needs.

The main problem with existing religions is that they do not serve the existing societies very well anymore. In fact many of them are just hold back social, cultural and political development. However, a new religion that would, for example, be based on science and philosophy needs not to include any of the old-fashioned fantasies and mythologies on which the existing religions are still based on.
A science-based religion or a modern "religion" that would be based on pre-Christian Epicurean or Stoic philosophy could be a reasonable collection of ideas that concern the very basis of human existence. Of course, one needs to pick and choose the ideas that can make up such a religion from the vast collection of ideas that humanity has created thus far. Naturally, a very hard question would be who would do the picking and choosing.

However, it just might be possible to create a 'pseudo-religion’, which just would offer a wide framework for use of many kinds of existing ideas. Members would then pick and choose the specific ideas that they would like to be included in their own version of that science-based ‘religion’.
The reality among the religious people is that people do just this kind of picking and choosing. They very commonly already endorse only those parts of a religion that they find palatable for just themselves.

A fact is that religions will not go away as long is the religious organizations do employ hundreds of thousands of people. Many of them have a well-paid and fulltime job of promoting and propagating their own version of blind faith.
Religions will not go away as long as they are taught to little children with no intellectual faculties of their own as 'greater truth', which they are never allowed to examine like all other areas of life are examined.
Religions will not go away as long as they are taught in schools like mathematics of physics to unsuspecting youngsters. Religions will not go away as long as they are part of the central power-structures in so many countries. They do even still form the central ideology for state-forming in some cases.

Religions will not go away as long as they are supported by official institutions in very many countries. Religions will not go away as long as they have special privileges to propagate their ideology. One should not forget that in some countries any differentiation from the official religion is still punishable with death.
Current religions will not go away as long as there is a class of people who see that they will benefit from their existence. The millions of members of existing clergy are one important part of this crowd. They will do their utmost to preserve the privileges. There privileges were given when people still thought that social stability cannot be achieved without a religion.

Zoroastrian temple  - Wikipedia

On the other hand, the ruling class of a society will greatly benefit from existence of a population that believes that their current oppression is ordered by some kind of 'god'. There are religious organizations like the Catholic Church in Latin America, which will actively destroy all political dissidence among this religion and will support the local ruling elites through thick and thin.
All in all, religion is never just a personal experience. Often this 'personal experience' can be also fine-tuned to serve the greater interests of the religious organization and in many cases the needs of the ruling elite in society.

In modern western societies, the role of religion as a tool of state has been greatly diminished and has even evaporated quite completely, but does not mean that this role would not exist in very many other societies.
A person can have deeply personal private religious experiences. However, as soon as a person joins a religious community, he enters another level. On this level religions do work as social and political phenomena. On this level, the sweet, loving personal message of a religion is often forgotten, and religion is used even as a weapon and a tool of oppression.

At this point, one should perhaps note that deists have never oppressed anyone. The deism of Baruch Spinoza or Albert Einstein or Thomas Jefferson was based on a personal religious experience only. It was not based an upholding of any kind of religious tradition.
They did not see the need for forming a religious organization to force their deistic views on unsuspecting children. They did not see the need for arranging funerals and weddings according to their religious views, either.

Wikipedia

So, a personal religious experience is a quite different thing as a religion. The game is changed totally if old religious books are taken at their face-value as guidebooks for public policy. Danger lurks, when interpreting these ancient books becomes a basis for forming the rules for an existing modern society.
Then the issue it is not the personal religious experience at all. The issue is how a belief in a religious message offered by others can make one act as a part of society. This is a completely different thing than a personal religious experience.

These experiences will not go away in a totally secular society either if they really are just private experiences. If they are used as justification for public policy, the situation is totally different. A science-based religion could be like deism. It could in practice be just a private framework for thoughts and ideas and a collection of higher ideals and goals for a better life and better society.
However, even this kind of religion just might be able the fill the void that could be left by the removal of the faith-based religion in many people’s mind. The fiercely individualistic core group of current atheists would never need such a thing.

This has been made clear in a recent discussion over the latest book of Alain de Botton called “Religion for atheists”.

However, there is a group of people who would benefit from a new clear-cut alternative for the existing religions. All atheists really do not need to think alike.

(This piece was refurbished on 10th of May, 2013)