Atheism is irrational.

[FallentoReason]

Whatever is rational utilizes either the senses, the intellect or both.

Atheism cannot deny God by using senses. For, to deny something by the use of senses is to search the whole physical reality, just as ruling out that there's no alien is to search all that is searchable which is impossible for us humans. But God, by demonstration of His effects, shows that He is beyond physical reality. Hence, it is the more that God can't be denied by the senses.

Agreed.

But, God can't be define, because if He has definition, He can't be God, because by demonstration of His existence through His effects, He is necessarily Boundless.

P1. God cannot be defined.
P2. If he could, he wouldn't be God.

C1. God is necessarily boundless.

P3. God can be defined as being boundless.

C2. God cannot be God