"I don't understand why lots of people nowadays like mocking Jesus.."
Because this is one of the few times in modern history when people can do so without fear of being burned at the stake. If the religious leaders had not been so scrupulous about maintaining their power for so long, people would have been mocking your god long ago.
"Listen.."
This should be good.
"Jesus was born before us more than 2000 years ago."
Assuming he was born at all. Aside from the bible there are no real records to suggest he even existed.
"We never see Jesus, or even know him personally but we heard his existence from the bible and Jews' history."
And this is supposed to help your case...how? Oh, and if you had actually read the Jewish prophets (instead of the select passages your pastor told you to) you would know that he wasn't the messiah they predicted.
"But what is the benefit for us if we're mocking him because we do not accept his teaching?"
Those who cannot be reasoned out of their fallacies must be ridiculed out of them.
"God never pushes you to believe him, he gives you free will."
Care to explain all the followers who were scared into religion by the fairy tale of hell?
"When some true christians or pastors commit sins, it's not always God's fault! Pastors/Christians are humans, they can make a mistake."
Odd that these same Christians and pastors never seem to be so forgiving of when other people, "sin." If they want to be understood as fallible humans, they need to extend that same courtesy to others.
"Satan influences a lot of people from believing God, Satan knows jesus more than us, he was ex-angel before the fallen, I know why some of us don't believe in supernatural things because we cannot see the spirits around us and we trap in physical body."
Satan, angels, the supernatural, you admit that these things cannot be seen, or presumably detected by some other sense, so how do you know they exist at all? In the past churches could force people to accept them, but now that their power is on the wane, you clearly have nothing to bolster your position.
"Also remember life is very short, someday we will see the real Jesus."
Okay, I was wrong, you have emotional appeals and threats of damnation to bolster your side. Get back to me when you have something substantial.