You don't understand.
The Ultimate Reality is God.
Every atheist argument is contingent on making God something other than this, so it is not meaningless. Quite the opposite.
And another. thing, there is no "my ultimate reality". The words are not meaningless.
Do you understand what ultimate reality means? There can only be ONE. It is what it is. Exactly what it means. How can words do it justice? That is what we recognize as being The One True God. The very God of Truth.
The church fathers didn't teach Calvinism. It isn't what the church teaches.
I don't normally link outside the site, but this article is first in a series that pretty well explains the issue specifically between what Orthodoxy teaches and Calvinsim.
It would be better to ask a Calvinist what they believe rather than the subjective interpretations and criticism of non-Calvinists.
I am a Calvinist. I am Presbyterian. I suggest that all true Christians are reformed in Doctrine.
A Calvinist is someone who simply holds the truths of the Scriptures as understood by the Apostles and taught by the church fathers. Augustine several hundred years later taught Calvinism years before Calvin came along.
The Core Essence of Calvinism is not predestination despite what anti-Calvinists say. In fact if you were to read Calvin's Institutes - four volume systematic theology - predestination hardly rates a mention. The core message of Calvinism, like the NT Scriptures is salvation by faith through grace. Trusting in the righteousness of Christ as Romans 10 clearly puts it. TULIP is an acronym that some use to describe Calvinism. I note it is primarily used today by non-Calvinists as a slander. But I like it and I teach it to my children in the following manner:
Total Depravity - I teach my children that this means all humanity has fallen into sin. That there is no one who is good. I don't teach like the link alludes to that humanity lost the image of God. That was a lie and a misrepresentation of what we believe. We hold the view that the image of God is in every human. Yet we also teach that all humans are sinful and that everyone because of this sin - deserves to go Hell.
Unconditional Election - I teach my children that this means that no one can earn their salvation. That in fact the only way to reconciliation with God is through Jesus. It means we don't have to meet conditions. We don't have to be a particular race, or colour, or sex, educational level, or political bent, or sexual orientation, or rich or poor, or even creed. We cant earn our way to heaven with money, or bribes, or importance, or intelligence, or by doing good works. Elections is entirely in God's hands.
Limited Atonement - despite some people's misrepresentation of what Calvinist's teach, this doctrine asserts primarily that not all people go to heaven. It is a doctrine of exclusivity. Yet it is a doctrine of assurance for believers. It teaches that those whom Jesus died for will be saved because their sins have definitely been atoned for. We would argue that unlimited atonement means that all people go to heaven because Jesus has paid the price for all people.
Irresistible Grace - We teach our children that those God has called and who recognise his voice - will be unable to resist his grace because grace is a gift that comes from God and is given without even the condition of receiving it.
Perseverance of the saints - We teach our children than those who are God's people will live lives in accordance with his will. Hence, though we don't believe good works saves any person, we take the view that all those who are saved will by virtue of their salvation want to and indeed be known for their good works. As James teaches - faith without works is dead.
Are we the only true church? No but we are part of the One True Church for we hold the truths of the apostles and the ecumenical creeds and we seek to live in accordance with the Spirit of God in his Word.