Abu Hamid Al-Ghazali writes:

“The mere physicist is like an ant who, crawling on a sheet of paper and observing black letters spreading over it, should refer the cause to the pen alone. The astronomer is like an ant of somewhat wider vision who should catch sight of the fingers moving the pen, i.e., he knows that the elements are under the power of the stars, but he does not know that the stars are under the power of the angels. Thus, owing to the different degrees of perception in people, disputes must arise in tracing effects to causes. Those whose eyes never see beyond the world of phenomena are like those who mistake servants of the lowest rank for the king. The laws of phenomena must be constant, or there could be no such thing as science; but it is a great error to mistake the slaves for the master.

As long as this difference in the perceptive faculty of observers exists, disputes must necessarily go on. It is as if some blind men, hearing that an elephant had come to their town, should go and examine it. The only knowledge of it which they can obtain comes through the sense of touch; so one handles the animal’s leg, another his tusk, another his ear, and, according to their several perceptions, pronounce it to be a column, a thick pole, or a quilt, each taking a part for the whole. So the physicist and astronomer confound the laws they perceive with the Lawgiver.
…
There are some who, failing to find God by observation, conclude that there is no God and that this world of wonders made itself, or existed from everlasting. They are like a man who, seeing a beautifully written letter, should suppose that it had written itself without a writer, or had always existed. People in this state of mind are so far gone in error that it is of little use to argue with them. Such are some of the physicists and astronomers to whom we referred above.” (The Alchemy of Happiness)

Notes:

We should be ready to discuss the question of God’s existence.  Atheist use logic to support their arguments and actively convert people to their way of thinking. The same tool should be used to either correct their faulty reasoning or to help sincere inquirers find their way to a possibility of believing in a Supreme Being.  This can make all the difference to the young people who are still open to see both sides of the question. Once they are converted to atheism, it is too late to expect objectivity from them. If a person wants to debate the subject just to show off his intellectual superiority, it is better not to waste one’s energy.

Reason alone cannot conclusively prove the existence of God, but it does not mean it should be disregarded altogether.  Other methods that lead to perfect certainty and enlightenment will be discussed later. 

Hazrat Mirza Ghulam Ahmad of Qadian (a.s) writes:
“Of course it is true that reason is not without its use and its benefit, and when have I ever said that it is useless? Nevertheless, how can we escape the obvious fact that through reason and conjecture, alone, we cannot attain the treasure of perfect certainty which can be achieved through the combination of reason and revelation…” (Barahin-e-Ahmadiyya, Part 4. pg. 79)

There can never be physical evidence of God because God is not a physical being, so methods of experimental sciences will not work here. But methods of logical analysis are used. These methods of logic have been investigated in detail, and they form the basis of all historical, legal, and sociological analysis.  

The Kalam Cosmological Argument:

Everything that begins to exist has a cause. This universe began to exist, therefore, it must have a cause.

The following will be discussed:

1.The universe itself is the cause.
2. The universe came into existence due to probability.
3. If not the universe itself or probability, then there is some other cause for its existence. It is the first cause.
4. The first cause must be uncaused.
5. The first cause must have certain attributes.

1.The universe itself is the cause.

The universe cannot exist before its own self to create itself. So since it exists, there must be something else that caused it to exist.
(The universe cannot be the cause itself because then the universe would have to exist and not-exist at the same time but that is illogical. Therefore the universe cannot be the cause of its own existence.)

2. The universe came into existence due to probability.
Probability does not cause anything to exist. Probability is the mathematical analysis of random phenomena. The mathematical description of the universes’ chances of existing does not imply that the mathematical formula was the cause of the universe coming into existence. The universe reflects mathematical structures, but mathematics doesn’t cause anything, it just describes the circumstances. Just as Newton’s Laws of motion describe what will happen to an object that is moving, but the laws themselves do not cause that object to move.

3. If not the universe itself or probability, then there is some other cause for its existence.

If we say something caused it, then you may say who or what caused that “something” to exist. There has to be a final cause. Otherwise, we will keep on tracing causes infinitely. Since we exist, therefore, it means the chain of causes has to end at one point in time. Where ever it stops, that is the ultimate cause of creation. We can conclude that for anything to exist there must be a final cause. For example, the domino effect, there’s always one single domino at the very end of the chain that triggers the rest of them.