Jesus/God/Allah/Zeus

Have you ever seen/heard/felt your god?

If no, why do you still believe without personal experience?

In other words, I don't understand "faith".

Faith as we Orthodox understand it, is not something that is grasped intellectually in the mind, it is something to be walked out.

You can think about these things all your life, and until you step out in it, none of it will make sense. You see but a shadow.

Our relationship with God is through Trinity, Father, Son, Holy Spirit. We abide in The Son, enlivened by The Holy Spirit, united to The Father in The Son.

Not on this mountain or in that temple but in Spirit  and Truth.

But to answer the question. Yes, and you could too. 

I suppose I have faith in some things, without real proof. Like that I have free will etc. So maybe i do understand faith a little.

If the evidence is enough to convince you, that is proof.

Proof is...

"the cogency of evidence that compels acceptance by the mind of a truth or a fact."

That being the case, it is important to note that something that is proof for one may not be proof for all. In fact, if you present all the evidence in the world to someone, enough to convince any reasonable person, and they stubbornly refuse to change their mind, they would not be lying if they arbitrarily claim, "I see no proof!"

For something to be proof, a mind has to change.

So I would say that you believe in free will because of proof. It has been proven to you.