Canadian apologist and open air evangelist, Sye Ten Bruggencate, is blessed with a gift of being able to explain hard-to-understand things in such simple terms, it's hard for me to explain.
So instead of me trying to explain, watch for yourself in this video as he not only gives solid answers to tough questions but, as always, he clearly conveys the wonderful gospel message within his discourse during a recent open air session in Victoria Park, London, Ontario.
I would suggest you get a pen and paper before you begin as you might be learning something here, as well. I do every time I hear Sye speak.
By the way, do you know someone who needs proof that God exists? Sye's website, Proof That God Exists is the place to go. Sye has a heart for lost souls and for the minds of intelligent fools. (See Psalm 14:1)
While you're at it, if presuppositional apologetics baffles you, there are resources on this website to help you to unbaffle yourself. It's worth the search.