The biggest pro-god arguments are summed up as: “ontological argument” , “ontological argument”, “design argument”
OTWO,
IMO, the most effective pro-god argument is a person's personal testimony regarding what God did for him after coming to a saving faith in Christ Alone.
My life changed from a drug addicted, cigarette-chain-smoking, burned-out rage-a-holic to a drug-free, peace-loving family-man. I can't take credit for this. God literally saved my life and possibly others as well.
Jehovah's Witnesses are not fundamental christians because they have no testimony of God actually living inside of them. It's all socialization and will-power. But quite apart from socialization and any will power of my own....God works inside me.
I was an unbeliever for a very long time, so I know how sappy that sounds to some, but it is true. And by the way, there is no other way to cross the chasm from agnosticism to knowing and experiencing first hand the presence of God except through Grace (on God's part) and faith in Christ Alone (on our part). It is a mutual collaboration of decision-making.