Greetings my young friend. When you get to be my age, 62, you’ll have the right answers but won’t think of them until later.
I think the answers you’ve received thus far cover the topic well and I have only two thoughts to add. First, as far as the existence and resurrection of Jesus go, clearly something astonishing had to have happened in the first century to have kick-started this whole Christian thing. People willingly died to defend what they believed they had witnessed and experienced. Granted, people of other faiths have also died en-masse in defense of belief, but this in no way negates the early Christian experience.
Secondly, your foundational question regarding the existence of God is one of my favorite topics. I have found, in my years of pursuing all avenues of Christian thought, that the greatest weakness in arguing for the existence of God comes down to definition. If we choose to define God as a being especially one with a definable place of residence, we are easily defeated by well informed detractors. It tends to back us up until we have no further retreat and can only state that we believe and that’s the end of it. But we will have done nothing to either give pause to the opponent or reinforce our own reasons for said belief.
When I think of God, and it has taken me many years to retrain the default images I was given as a child, I no longer picture a wise and powerful Santa Clause-like man sitting on a throne “somewhere up there”. Rather I try to imagine the massive energy that powers the universe, that supports all known life, and which permeates all of existence. This energy, looking at it in a very basic way, is to my mind, conscious, aware, and involved. It’s what we, through the ages, have called God but is not in any way related to most of our preconceptions of God.
Bishop Robert Barron quotes Augustine saying, “If you can understand God, then that is not God”. It’s simply beyond the scope of our human mind to comprehend so it seems to me we are not expected to convince others of God’s existence. God just IS. There’s really nothing more I can add. Blessings to you.