A true transcendent and infinite God knows infinitely more than us and is able to create an infinite multiverse of realities. By assuming any one religion known to man is the only truth, you are limiting the scope of God to the scope of man. For this God to only create one universe where one religion is true would be to only use an infinitely small fraction of his potential, because any limitation at all is infinitely limited relative to the infinitely unlimited potential of God since anything that goes on infinitely is inherently infinitely broader in scope than anything which is finite, no matter how broad the scope of that finite thing is. The truths of all religions known to man are finite in scope, with the sole exception of the truth of the infinite and transcendent God himself. So to disprove the proposition it would be necessary to demonstrate that any one religion is a religion than which it is impossible to conceive of a greater religion, which is impossible because Infinite God can create greater religions ad Infinitum and never exhaust his capacity to create greater and greater realities.
In the previous paragraph I spoke of God having potential as if it were hypothetically possible for him to have unfulfilled potential. The very notion that an infinite God could have unfulfilled potential is impossible though and further demonstrates my point. For God to have unfulfilled potential violates divine simplicity and violates the very notion that he is infinite. An infinite creator creating finitely is a contradiction, he will go on creating endlessly or his creation stops somewhere infinitely before his capacity to create is fulfilled. This is infinitely more ridiculous than a master painter making one brush stroke and then never making another in his life. It is important to grasp that the largest number imaginable is still infinitely smaller than infinity.
Divine simplicity is a theological term that refers to the perfect wholeness of God. God's essence is not made of parts or divisible, for if it were those parts would be more fundamental than him. The wholeness of God is at the very core of reality itself, and God is assumed to be infinite in this debate. Therefore the truth of God goes on forever, no one religion contains the fullness of God and an infinite God is not limited to any one paradigm. Even the greatest religion and the greatest reality is a puny, pathetic speck of dust compared to the fullness of the truth and the creative power emanating from the Infinite creator. If God has unactualized potential, there is a distinction within his essence between the actual and the hypothetical nature of God and thus the divine simplicity of the infinite God's essence is compromised.