How/when did you feel you knew god existed? I'm so keen to hear!
For me it was when I began to look into the bible for myself. I had heard an awful lot about the book but never really read anything other than the Christmas story at school, or psalm 23 which I found strangely comforting when life was really hard as a kid.
It started with realising one thing I thought the bible said wasn't true: the bible didn't say you have to be good enough to qualify for heaven. In fact, it said there is nothing you can do to earn your way to heaven. It is a free gift. And like any free gift there comes a choice. Do you reach your hand out and take the gift, or do you turn your back and refuse?
I didn't want to accept any free gift if it wasn't based on the truth though, as I didn't want to waste my time. Or my life, thank you very much! But I was intrigued about what was offered and so looked into it further. I saw that the free gift was total and utter acceptance from a Holy and powerful God. A God that by all rights should be rejecting me, not the other way around! But yet he wasn't. He was doing the opposite, and reaching out to me in love.
The next step was to decide whether I could possibly believe this is who God really is. But it's like calling for a doctor. When the doctor arrives you see his ID, and know he's responded to your phone call, but you also know he could just be pretending. Maybe a neighbour heard your phone call and decided to masquerade as the doctor so they could break in and get your money.
So at that moment you have a choice. You either take the risk that he is the doctor and let him in to treat you, or you slam the door shut and yell "I don't believe you're the doctor, send me the REAL one!"
I then looked further into the ID claims that God makes in the bible. I read some of the many prophesies and found to my astonishment they were found to be true. I read how the historical and archeological claims were accurate. This book was starting to look pretty reliable to me. I then checked out some atheist websites where they cut and paste biblical inaccuracies. They sounded pretty convinced but it didn't take long to see they'd twisted the context quite badly. This also supported the truth and reliability of the bible.
I then saw how John 3:16 says "for God so loved the world that he gave his only son, so whoever believes in him should not perish but have eternal life." I saw how it doesn't say 'whoever goes to church' or 'whoever loves a good life' or 'whoever is christened/confirmed/baptised' it was 'whoever believes'. I looked up the word 'believe' and saw it described words like; to trust in and rely upon with full assurance. I realised we all believe something, as in, we all trust in and rely upon something. If not God then a false god or a person (usually yourself). I've always been pretty realistic about humanity and myself, and whilst seeing my value, I also see my inadequacies (all those new year resolutions over the years!). I understand it can be uncomfortable to be that honest with yourself though, and some find it harder than others! It felt like I was standing at the top of a cliff and an exciting but scary prospect at the idea of trusting in God, I can see why it's called a leap of faith sometimes!