"invisible friends in the sky"
This is a very immature and simplistic way of describing Christian, Jewish and Muslim faith - and very possibly most other faiths, too.
When a man stops believing in God he doesn’t then believe in nothing, he believes anything I think thes is very true - look at all of the people who don't believe in God, but put their faith in "spiritual" things like smudging, and crystals, and flower remedies etc. And a lot of people who claim not to be religious but claim that they are "very spiritual" ( 
).
I am a practising Christian, and have been blessed with some deeply moving spiritual experiences. I honestly think that many people have had such experiences but have dismissed them, or not even noticed them because they are so focussed on the material world. (Or have kept quiet about them, or refused to acknowledge them even to themselves because they fear other people's reactions.)
Religion has not in itself caused wars, though many have been fought in the name of one faith or another - but I don't believe that God (as I believe in God) wants this. I won't pretend I can read God's mind, but I think that it is humanity corrupting and deliberately misusing God's commandments - individuals perverting faith for their own ends and via their own interpretations - that has led to "religious war". If there was no religion, they would have found another "reason" to fight.
God gave humankind free will - that brings with it responsibility for one another and for the beautiful planet on which we live, with all of its diversity. We can't second-guess God - God is not like us but bigger, but is a different nature and substance altogether. As mortals we can't even begin to imagine what God is like, because God is so much more and so very, very different .
We can't explain the evil in the world, but as the Book of Job shows use can't read God's mind or understand God's great purpose - we are, however, learning that creation is finely balanced and that by tipping the scales (e.g., by cutting down rainforests and poisoning oceans to feed our greed) we are irreparably upsetting that balance.
Jesus said "Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the law and the prophets."
And even if you don't believe in God - any god - you can't really argue that the second of these commandments at least, is one we could all do with keeping.
"Invisible friends in the sky" is childish rubbish. God is in every part of creation and is not sitting on a cloud above us watching what happens. God is, rather, the creative force which has shaped, and continually sustains, the universe.