It's a joke. Sort of.
Christians really like to use God's mental image and create their own imaginary friend / companion. They thought that if God's on their side as their ally, what could possibly stop them. It's a good motivation to do things well, and a decent coping mechanism when things go south.
But what if we think of God as our nemesis? Imagine that.
First of all, instead of doing that mental gymnatics on whether God was really responsible for your failure, you could just straight up credit God for all the fucked up things that happened to you.
Didn't finish that important report before the deadline? That was God's doing. Got a bad performance review? Also God's wishes. Got fired for underperforming severely? God planned it every step of the way. This is a damn good coping mechanism: how do you suppose *I* make things go differently? He's the friggin' God.
What about when good things happen in your life? I'd like to think that I went against the divine odds on these occasions. I conquered these things, for once, and when that happens, it's fine time to celebrate by rubbing it on God.
Moreover, I like the feeling of being an underdog ya' know? Here goes the person who has really not much in a way of resources, and he managed to beat the odds every now and then. The champion needs to beat everyone to be remembered. But the underdog only needs to defeat the champion once to stay immortal. Checkmate, God.
Also, some clarifications: when I say that I'm God's nemesis, I'm not saying that I align with Satan / I'm Satan himself. I'd like to think that God and I had a good business relationship, but through honest yet irreconcilable creative differences, we had to part ways. And an ex-business partner being petty means that you'd get sabotaged every now and then.
So there you have it: God as a nemesis is a damn fine alternative to the boring old God-is-your-bestfriend trope. Is this a coping tool for a normal functioning, and stable adults? Perhaps not. I guess having an imaginary figure be the center of your life can make you sound like a complete tool. Then again, everyone likes a good imaginary friend. Me? I prefer to have nemesis.