Consider the argument that "everything which begins to exist has a cause for its coming into existence, and the universe began to exist, therefore the universe has a cause for its coming into existence". Someone would have to know everything in order to even begin to show that "everything which begins to exist has a cause for its coming into existence". Further, the argument just assumes that the universe has a cause because everything else does. Perhaps everything which begins to exist does not have a cause because the universe does not. Aside from these difficulties is the difficulty of proving that the universe indeed did begin to exist and has not existed eternally as many believe that it has.
Even if the argument works, what has it really shown? The universe has a cause...? So what? How do we know that this cause did not happen and then go out of existence? How do we know that it still exists? Why only one cause and not many others? What else can we really know about this cause? If someone honestly wants to show that the Christian God exists, this is not the argument to use, because it fails miserably. Even if the argument succeeds then it has proven the existence of any number of gods unlike that of Christianity. So those gods exist?
When we look around us we see design and should infer that there is a designer. One designer? Why not trillions? When I look at something which has been designed by humans I only know that it has been designed by them from experiencing the world around me, however I have never experienced God creating or designing the world. There are also many parties involved in the creation of most everything we see. So again, why only one designer? Aside from this, who is to say that it is the Christian God who has designed? How do we know that this designer is still in existence? The supposed design around us can be seen to stem from ancestry, so why can this not go back forever? It is not as though we make an inference to a direct designer being involved in a human being or a plant being born; it all came about through natural causes. Why should the whole world be thought of as being any different in this respect?
The historical facts surrounding Jesus do not prove at all that God exists, even if it is shown that a resurrection occurred. Personal religious experience does not prove the existence of God, since it would therefore prove the existence of many other gods all inconsistent with one another since people of all different religious faiths claim experiences as well (just as the arguments mentioned above also do).
I do not think that any of this is very difficult to understand. These arguments are poor and yet Christians use them over and over again.
Many also insist that they will prove God's existence without using the Bible, whatever that means. I have heard the argument before that all of God's words are without error and the Bible is God's words so the Bible is without error. The argument is valid but how can someone show that any of it is true?
How do you know that God's words are without error and how do you know that the Bible is God's words? I've heard all of the stuff about 66 books 1500 years over 40 authors manuscripts prophecies etc. but none of it actually shows in any way that the Bible is God's words or that God's words are without error.
The Christian God is also said to be all powerful and all good, yet evil exists. Why? The answer cannot be free will, because it would follow that either 1)there will be evil in heaven or 2) there will not be free will in heaven. Both of these are inconsistent with the explanation that the reason evil exists is because humans must possess free will (or else they are "robots").
Why do you believe?
I can assure you it is not because of any of the traditional theistic proofs.