Buddha found not the Buddhism
Buddha found the Dharma
Dharma means Noble Truth
Hence, Buddha found the Truth

The Truth is always True
No matter one understand it or not
No matter one believe it or not
No matter one accept it or not
No matter one like it or not
No matter one deny it or not
No matter one is Christian, Muslim, Buddhist, Hindu, non-religious
The Truth will always, without exception, applicable to those who/which are governed by it.

Just like, there were 5 people
A Christian
A Muslim
A Buddhist
A Hindu
A non-religious
5 of them standing on top of 101-story of a building,
It will be false for the Christian to say “I will not fall down if I jump”
It will be false for the Muslim to say “I will not fall down if I jump”
It will be false for the Buddhist to say “I will not fall down if I jump”
It will be false for the Hindu to say “I will not fall down if I jump”
It will be false for the non-religious to say “I will not fall down if I jump”

Because there is a Truth that governed all of them, Law of Gravity, which pull them all down.

Again, because
The Truth is always True
No matter one understand it or not
No matter one believe it or not
No matter one accept it or not
No matter one like it or not
No matter one deny it or not
No matter one is Christian, Muslim, Buddhist, Hindu, non-religious
The Truth will always, without exception, applicable to those who/which are governed by it.