Nah, you're making simple things complicated again. Making a case for gods existence isn't so hard. Whenever you witness, measure, feel or what ever Christians do, the presence of God, you can if you judge it so, use it as proof of gods existence. Like my Cambridge friend points out. Logic is just a tool. If you put garbage in you get garbage out. But if you have taken the leap of faith that your evidence you put into the logical formula is irrefutable then it isn't garbage and your logical conclusion for the existence of god is solid.
Here's an example of perfectly valid science using solid logic. In today's scientific climate it doesn't have the critical stance required to be called "good science", but it is real science none the less.
1. Observe some aspect of the universe. (Water Boils when heated to 100 degrees C)
2. Invent a tentative description, called a hypothesis, that is consistent with what you have observed. (Water boils when heated because God wished it so.)
3. Use the hypothesis to make predictions. (Water will Boil when I heat it, God will cause it to Boil.)
4. Test those predictions by experiments or further observations and modify the hypothesis in the light of your results. (I heated water, God Willed it to Boil)
5. Repeat steps 3 and 4 until there are no discrepancies between theory and experiment and/or observation. (God made my water Boil Every time except for once, the devil put out my flame)
The big question is: have you witnessed God or a manifestation of god? When you witnessed this god force: how did you go about identifying it as a god? How did you tie that manifestation to the deity as explained in the Vulgate Bible? How did you tie that deity to the moral values explained in the Vulgate Bible? As you no doubt realise, we can go a lot further than this in our scepticism and question if and how the various parts of the Bible is connected to the God you witnessed.
So even if you have enough proof to convince yourself of the existence of, not only the supernatural but also a "God", you still have a long road to travel before you end up at Christianity. And you made such a strong case for agnosticism that I'm wondering how it is possible for a person as open minded as you to pigeon-hole yourself as holding such a spe******ed form of theism? It's not only the Christian god but a very specific form of Christianity.
As my Cambridge friend pointed out. Without the required support, any faith is a massive leap of faith right out into the dark. Others can attack your faith, but as long as you've taken the necessary steps to support your religion rationally you've got no reason to waver in your faith. Me personally, I'm very sceptical if that is even possible to support theism in this way and I'd love it if you'd show me the steps you took to support your faith.
edit: You could admittedly take what figures of authority say as evidence to, (like a friend you trust for example). But that makes you a sucker. Especially considering the case for the existence of anything supernatural isn't particularly solid yet. And you can't take incomplete or unconvincing evidence and judge it by sheer numbers. That is probably the most common error in logic. Each case of evidence has to be separately judged.