Is God Necessary?

Is God necessary?
Why should there be a God? Ishwara?

Let's first look at the opposition to the existence of God raised by rationalists and atheists, because unless there is a strong opposition, your own arguments become weak. Like how an absolute majority government with a weak opposition or a dictatorial regime would behave.

Our shastras don't just preach or give you a set of arbitrary rules. The approach of our shastras is that they tackle oppositions, which is called purva paksha, and through that establish the validity of principles.

So, first we will look at the arguments against the existence of God.

One argument is that the creation of the world is just accidental. It just came into existence without any reason or intentions. It runs without any controller behind it. Whatever happens in the world are random events—a large number of random events—they only exist.
Sarvam kshanikam.
They are not related to each other. There is no connectivity between events, there is no past, there is no future—only what you experience at the present moment is there. Past and future are just creation of the mind.

As per this, there need not be a God.

Another school of thought would accept only what can be perceived through eyes, ears, nose, tongue and skin. Other than these, everything else is just creation of mind.
If you can see God, God exists. Otherwise, not.
There is nothing called a soul or atma also, which we consider as the traveller in the vehicle called body.

For us, the traveller enjoys the cool breeze that comes in through the window of the vehicle, and also suffers the jolts on a bumpy road. But like how a car of Indian origin is restricted to ply on the Indian roads and cannot freely ride into the neighbouring country, we say there is a large framework of control in place.
But at the same time—which road to take when you have a choice, the highway or bumpy road, at what speed to drive—these are all in your hand.

The rationalists won't accept this larger framework of system. They will only accept the validity of the small decisions that you make from time to time.

Similar arguments are nothing new.
Gita in Chapter 16 lists some of these rationalist arguments:
असत्यमप्रतिष्ठं ते जगदाहुरनीश्वरम्।
अपरस्परसम्भूतं किमन्यत्कामहैतुकम्।। 16.8।।

Many of these arguments will prove to be futile just by looking around you.

There is a clay pot.
Did it just appear all of a sudden where it is sitting now?
No.
There was clay before that. Somebody used the potter's wheel and made it into this shape and size.

So, the presence of the clay pot as it is—of a particular shape and size—just accidental? A random event?
No.

There are three things involved that brought the pot into existence:
A material called clay which transformed itself into the pot. Let's say it is just a raw pot, not cured.
Can a lump of clay just turn itself into the pot?
No. The potter has to work on it.

There is action and effort involved. Without that, the lump of clay will not turn into a pot.

There is knowledge and intelligence involved.
I won't be able to make a pot. I have not learned. I am not trained to do it.
I will try to take the lump of clay and try to do all sorts of things with my hands.
But I don't know that it has to be kept on a wheel, and as the wheel rotates, using my hands, the clay is to be shaped into a pot.
This knowledge I don't have.
Will I be able to make the pot?
No.

Pre-existing material in some form, action, and knowledge are required to bring anything into existence.
These three we call them Ishwara, Para Brahma, Parmatma—material, energy, and knowledge.

Nothing can be random or arbitrary.

This we have spoken about only for a clay pot.
Think about the trillions of objects in the world—living, non-living, movable, immovable, big, small—all their interactions with each other.

A human being, through thousands of generations, still gives birth only to a human being—not a monkey or a lion.
A tree flowers and bears fruits according to seasons.
Sun always rises in the east—not for a day in the east.
A waxing moon never reverses its growth midway and starts waning—not before Purnima.
A man always sees with his eyes—not through ears.

There is a system in place.
Without a control, no system can function.
This control, this controller, this control system is what we recognize as God.

In a computer, there is an operating system which controls all that the computer does.
This is not visible to you.
What is visible to you is just the apps, the applications which are of day-to-day use to you.
Will you say, where is the operating system?
Show me.
DOS or Windows don't exist, because I don't see them.
Only Microsoft Word and Paint exist?

Operating system exists. And the computer engineer can access it. He has knowledge to access it.
He can access so many things that you don't know how to.

These arguments are also childish like this.

Ultimately, what we recognize as God is—material, energy, and knowledge.
We go one more level deeper and say that both material and energy are just derivatives from knowledge.
This is the concept of God as per Sanatana Dharma.

You call him or her by whatever name you want—Ganesha, Shiva, Vishnu, Durga—whatever.
Doesn't matter.

Ramaswamy Sastry and Vighnesh Ghanapaathi