A sceptic's guide to religious belief in the 21st Century
God is an omnipotent, omniscient, omnipresent being that created the Universe in a Big Bang about 13.7 billion years ago. We know this for certain because God specially created us so that we could say so. However God didn't need us to say so until about 13,695 billion years after the Big Bang; so he either carefully tuned the Big Bang initial conditions or, once having set things in motion, he dropped by every few billion years, firstly tweaking cosmological evolution to produce the Earth, and then biological evolution on Earth itself. God exists outside time and space yet manages to intervene in time & space. This is said to be "moving in mysterious ways".
God, existing outside time & space, is of course invisible and undetectable yet we know at least something about him because it is said we were created "in his image". This doesn't mean we look like him, (don't be silly) so the fact that he is male needn't cause us females too much angst, especially as he is invisible.. Maybe it just means we think like him. Even so, perhaps as existence was boring, he also made us so we would sometimes think naughty thoughts and do naughty things, and he knew all along that we would. He also wanted us to know that he, being God is much godlier, even infinitely godlier, than us and would therefore be forgiving us for all our naughties since he made us like that.
God signalled his forgiveness in a way that is rather difficult to understand. One first needs to know that God is composed of 3 parts (but definitely not a tribunal. that's a real no-no; this is strictly a Monotheistic religion we are talking about here). To make sure there is no confusion we call God a "Trinity" and the three parts are known as "God the Father"; "God the Daughter"; whoops, sorry "God the Son", and God the Holy Ghost.
That having been established we can get back to God's scheme for forgiveness. By means we needn't go into here, (save that it involves the Holy Ghost and even some Christians have doubts about its veracity,) the God Trinity decides ( I assume it was a joint decision) that the Son bit should appear on Earth as a man called Jesus. On Earth in a backward, illiterate corner of the Middle East, his chief occupation would be wandering about telling everyone how wonderful God was, how they should behave, and throwing in the odd miracle to get attention. Being God he already knew of course that that would greatly annoy the existing religious hierarchy and ruling power and would eventually get him horribly tortured and crucified to death. This however was all part of the Godly plan. By sacrificing himself to himself he apparently atoned for all the sins he knew the human race were going to commit from when he made them half a million years previously into the indefinite future. We are so lucky!
To absolutely clinch matters he got up from his tomb a few days later and walked about a bit before ascending finally into Heaven in a bright light. This greatly impressed his groupies who went on wandering about for years stirring up trouble until a later Roman Emperor for the sake of a quiet life decided to humour them. And the rest is real history.