'I know for sure that Gravity Exists'
You believe that you know for certain that gravity exists.
In order to know this you have to use your reasoning. How do you know your reasoning is valid?
You are also assuming that the law of gravity will continue to exist in the future. But in order to know this you need to have a valid reason for the uniformity of nature continuing in the future as it has in the past. What is your reason for assuming this? If you cannot give a good reason for the uniformity of nature then you have no justification for knowing any scientific knowledge.
In order to know this you have to use your reasoning. How do you know your reasoning is valid?
You are also assuming that the law of gravity will continue to exist in the future. But in order to know this you need to have a valid reason for the uniformity of nature continuing in the future as it has in the past. What is your reason for assuming this? If you cannot give a good reason for the uniformity of nature then you have no justification for knowing any scientific knowledge.
Later you will find out how deep the absurdity of denying God goes when I explain the massive problem with assuming uniformity based on past experience. But first I want you to consider the question:
How do you know your reasoning is valid?