What makes people cheerful? God makes them cheerful at the cheerful times. When they doubt God, then they become cheerless. If they trust God, they can be cheerful in many troubles. God makes them cheerful.
People are cheerful comfortable conditions of life and lack of health problems, and not faith in God. Many atheists are much happier than religious people. It seems to me that sometimes religious people are unable to enjoy life because of the stupid prohibitions of their religion.
The big difference is that if the person is a Christian, his happiness goes on into eternity, while the atheist's happiness ends at death if not sooner.
We are all going to die and end up in the same place no matter how much you want to believe we are special, I know it's hard to admit but it's the reality, there is nothing beyond death.
In addition to the proof that God exists that I have been showing you at the "Scientific proof that God exists?" thread, at https://bitcointalk.org/index.php?topic=737322.0, there is scientific proof that the Bible is the Word of God.
The Bible proof is a bit more complicated to explain, and it is impossible to explain to a person who doesn't understand that God exists.
The strongest proof for God is not a scientific proof. It is a relation proof. When a person accepts the Spirit of God into his/her life, the person has personal relationship with God, and personal proof.
Those who don't accept the Holy Spirit don't have that proof. That's why they think that such proof is make-believe.