There are two distinct questions here, and and the second follows logically from the first. But before we start, we need to resolve a background issue.
In asking this question, we're basically asking
"What kind of proof will be good enough? How much proof is
needed?". When we talk about proof, we're talking about
establishing some degree of certainty about something.
Scientific knowledge is based on repeated observations, but scientific knowledge is only one kind of knowledge. Other kinds include historical knowledge, philosophical knowledge, moral knowledge and personal knowledge. These types of knowledge lie outside the bounds of scientific knowledge.
For example, take historical knowledge. Can you prove that King Henry the Eighth existed? Using the scientific approach of observation and repeatable experiments, impossible! But using historical methods, it is certain that he existed beyond a reasonable doubt. This phrase is the key. While not one person living today has ever seen King Henry the Eighth, we know he existed beyond a reasonable doubt. This is why in law courts, a jury must be convinced of guilt beyond a reasonable doubt, not beyond a shadow of a doubt.
So, when we look to prove whether God exists today, a scientific approach will not work. The amount of proof needed is enough so that we can say: "God exists beyond a reasonable doubt".
We can now restate the two questions above:
Is it reasonable to accept that there is a 'Higher Being' behind this universe? If so, how do we know 'what' or 'who' the Higher Being is? Is There A Higher Being?
There are many different arguments for the existence of a Higher Being, none of which rely on the Bible, and none of which can be scientifically proved. Here are a few:
When we look at anything which has a design, we rightly conclude that it had a designer. Somebody designed chairs for a purpose. Somebody designed a glove to fit over a hand. The universe, and particularly human beings, show an unbelievable amount of design. This points to a Designer.
Humans have a complex personality. It seems (and is) absurd that such complexity could have emerged from nothing, with no cause. Rather, the human personality would need to be made by a Being with the same, if not greater, complex personality.
Everything we can think of, and which we encounter, has been caused by something. Every effect has a cause. In something as complex and awesome as the universe, there is no difference. The Big Bang Theory does not destroy this argument, for no-one can explain the cause of the Big Bang.
If there is a concept of something, this implies that the something does exist. For example, there is the popular concept of 'true love'. Although this concept might often seem elusive, the fact that we have the concept of true love in our heads, points to the real probability of the existence of true love.
The sense of morals which most people have
'built-in', points to the existence of a moral Maker. More than
this, the other option of evolution, has no way of explaining how
morals came from pond-slime, and ultimately, from nothing.
These arguments, on their own, and even collectively, cannot possibly 'prove' that God exists. However, they provide enough of a starting point to accept that there is probably a Higher Being of some kind. At this point, we are in a position to try and answer the second question.
To discover this (if such a thing is possible for
us to discover) we can approach it by starting from what we know,
and moving to what we don't know.
1. This physical universe was caused by something 'beyond' it.
Everything we encounter and can think of, has a cause. The words you are now reading were caused by a person typing them on a keyboard. Cars move because they have an engine. A tennis court didn't suddenly come into existence one day. It was built by someone. People speak words because their brains instruct the muscles in their mouths to move. It is reasonable that the world we can see, and of which we are a part, also has a cause.
2. This 'beyond cause' has to be at least as complex as this universe.
In all the universe, the most complexity is found in the human body, and specifically, in human personality. This means that the cause of this universe must be at least as personal as we are.
3. This 'personal cause' [from now on, referred to as 'Higher Being'] brought about a universe with a number of characteristics:
The universe has an amazing amount of unity and diversity in it. Imagine life without colour, music and rainbows. Imagine not being able to imagine.
Humans have emotions and intellect, which bring about hopes, dreams and fears. They also bring about the recurring Why Am I Here? What Is My Purpose? questions.
Humans have the ability to make their mark on this world, for good or for bad. This is why we see extremes such as Adolf Hitler and Mother Teresa.
Humans are not automatically 'clued in' about the existence of a Higher Being. But the incredible number of spiritual paths points to the fact that most people are interested in finding out...
4. The only reasonable way we can expect to find out who this Higher Being is, is if the Higher Being chooses to reveal him/her/itself to us.
We would expect either a direct communication from the Higher Being, or perhaps an indirect communication through a 'middle-man'.
We would expect to be able to understand the communication.
We would expect that many, many generations would have received the communication. In other words, it would be strange and suspicious, if the Higher Being chose only to communicate to the last few generations, and not the thousands of generations before that.
5. When we survey the historical landscape, a number of candidates for such a communication appear. However, on closer examination, many of them disappear.
Of the several major world spiritual paths, (go here for more details) only some claim that the universe was brought about by a Higher Being.
Animism is the worldview that spirits and forces have power over human lives, and that humans must find out which spirits are impacting them. But there is no Higher Being behind it all, and therefore no communication.
Atheism is the worldview that there is no Higher Being of any kind. Since no-one has all knowledge in the world, this is not a position that can be defended or taken seriously.Clearly, there is no communication, as there is no-one to communicate.
Buddhism is the worldview that there is no Higher Being of any kind, and that the universe has no beginning or end. Guatama Buddha never claimed to be 'God', and he never claimed that Buddhism would lead to 'God'. Since there is no Higher Being, there is no communication.
Christianity is the worldview that there is a personal God, who has communicated to humans through the Bible.
Hinduism is the worldview that the universe is an illusion. Some Hindus believe there are 33 million god, while others believe that there is one ultimate reality, Brahman. Yet, Brahman is not a personal Higher Being. He is more like a force, who is completely uninvolved with the universe (which is an illusion anyway). While there are sacred writings in Hinduism, there is no communication from a personal Higher Being.
Islam is the worldview that one God, Allah, brought everything into existence. Through the prophet Mohammed, Allah gave to humans the Koran. Allah has personality, but he is not the same God as the God of Christianity. Clearly, Islam is a candidate for a communication.
Judaism is the worldview that one God, Yahweh, brought everything into existence. Yahweh communicated to His people Israel, by inspiring various people to pen the Old Testament (the Jewish Bible).
Various more recent spiritual paths have emerged, such as Mormonism, Jehovah's Witnesses, Christadelphianism, Scientology, Christian Science, the Unification Church, etc etc. All of these must be rejected as candidates, since they have only emerged in the past 1 or 2 centuries. Surely a personal Higher Being would not wait until the very recent past to communicate with people...
From the survey above, only Christianity, Islam and Judaism emerge as serious contenders for a communication from a Higher Being. We can narrow down our options even further, by asking what such a communication might 'look like'. Here are some pointers that may help. It would probably:
be within history - so we could have any access to it at all
be recorded - so we all could have access to it
be translatable - so anyone in any language could have access to it
be in everyday language - so that understanding was not restricted only to a certain elite
be a written communication - since an oral communication only might go the way of a Chinese Whisper....
make some 'way-out' claims - to differentiate it from the sacred writings of a normal person
offer some evidence to back up those claims
have an authoritative and/or exclusive tone
affect people quite strongly - either causing feelings of comfort, or anger.
Of the Bible (Christianity), the Koran (Islam) and the Hebrew Scriptures (Judaism), the one that stands out is the Bible. The difference with the Bible is that it focuses on Jesus, a carpenter from the Jewish town of Nazareth, who told people that he was God in the flesh. We have looked at the evidence for these claims elsewhere, and it is more than a reasonable conclusion that Jesus was exactly who he said he was: God.
The original question asked whether it could be
proved that God existed today. If Jesus had died, and
stayed dead, we would have to say "No". But Jesus came back to
life, and lives today. This is the biggest claim for him being
God, and it is understandably also the most controversial claim
debated among people today. The message Jesus communicated with
us is the same today as it always has been.
I, Jesus, have come so that people might have life, and have it to the fullest.
First, we concluded that it is definitely reasonable to accept that there is a Higher Being of some sort. Next, we asked whether it was possible to discover who this Higher Being was. We then showed that beyond a reasonable doubt, this Higher Being was Jesus. Remember, that we only need to establish this kind of 'proof' beyond a reasonable doubt, not beyond any doubt. God does exist today, and the personal, moral and philosophical knowledge of many people adds further evidence to this. No-one can ever prove that God exists by scientific methods. We should be thankful for that: what kind of 'God' would that be? No mystery, nothing hidden, everything reducible to a set of principles. God is far bigger than that...