Also to say that the absence of something does not prove anything nor is it a basis to conclude that something doesn't exist.
GBRK, The same goes for saying something exists. You can't just say something exists without any proof whatsoever and get upset when people don't believe you.
Fist of all I by no means get upset when someone disagrees with me or takes a stand contrary to what I do. I believe many people disagree on various things but are they respectful in doing so? Respect usually begets respect and visa versa as some might say.
That said I would disagree, in part, with regards to the statement regarding something existing because with regards to the physical existence of something then that is very easy to prove for you see it or can touch it so there isn't the absence of matter but the presence. Now with regards to the statement that something exist where there isn't any tangible physical evidence you can see or touch then I agree with your statement. However that doesn't mean that sufficient evidence or proof doesn't exist for the person making the statement. Other's might claim that the evidence or proof for that individual is just a delusion but for that person it's just as real as if they can touch it.
An example is Love itself. You claim you love someone, whether it be a spouse, mother, father, etc. but you have no ability to prove it, no ability to provide evidence that you can show someone. Some may claim that you can prove love because of your actions toward another but then the same could be said of God for it all comes around to if you believe the person or not. It is also said that there is no proof or evidence that God is real or tangible evidence for the believer that their faith is in something that is real and true.
Romans 8:16 (HCSB)
16 The Spirit Himself testifies together with our spirit that we are God’s children,
Ephesians 4:30 (NCV)
30 And do not make the Holy Spirit sad. The Spirit is God’s proof that you belong to him. God gave you the Spirit to show that God will make you free when the final day comes.
2 Corinthians 1:22 (NCV)
22 He put his mark on us to show that we are his, and he put his Spirit in our hearts to be a guarantee for all he has promised.
While for the Christian there is no way to prove anything. We can make statements or testify of what we experience of God's changing power in our lives but as I indicated above to others it's just a delusion. The above verses though refer to the proof every Christian has of God's existence or of their salvation. It is God's Holy Spirit dwelling within our own bodies along with our inner spirit/soul. There is no physical way to prove such but just as when we say we love someone it is alive and real unto us/the person that has it.
So while you are correct in part, saying that there is no way to confirm it the only real confirmation comes for the person themselves and that is God's Gift unto those who accept Him and believe in Him. The ONLY way a Christian can know God is by God's Holy Spirit that is given unto them at their conversion/salvation.
For the person that is not a Christian, does not believe in God or that may be looking the only proof or experience that they will have with God (God's Holy Spirit) is that time of conviction where God, by His Holy Spirit, reveals unto that person their Spiritual need to reconcile with Him, recognize their inadequacy and inability to satisfy God and their need for Salvation. Only at that moment in time can those who are not in God's family, not Christians, or not God's chosen, have any proof or evidence to cause them to question their beliefs.
For some who look for God to directly talk to them, address them, no proof is sufficient for them to cause them to rethink their own belief so it is only when God's Holy Spirit ministers unto them through conviction of their mind/heart will they have that meeting with God. For others creation itself, the order of things and nature itself creates the question of who keeps things in order or who created such. Belief is a very personal thing for each and every person. It is not up to me or anyone else to judge another's personal beliefs and certainly I don't take offense if someone doesn't believe. I can only relate what it is to me and what I have experienced and let it rest with that. I believe God is sufficient enough and will reach out to those who seek Him, that I believe, but for each person it is up to their own self whom or what they accept or believe in and what justifies their reason for what they believe for it's different in every person.