Ok my point is what makes your or any opposing "theory" correct and the other wrong wrong??
Evidence.
The " theory " of evolution the big bang "theory "
Both theories are supported by multiple lines of independent, corroborative evidence. For instance, the big bang theory is supported by:
1. The observed expansion of the universe.
2. The observed homogeneity and isotropy of the universe.
3. The observed cosmic microwave background.
4. The observed primordial light element abundances.
5. The observed relationship between the fluctuations in the cosmic microwave background and the distribution of structure in the nearby universe.
While I'm not going to go into the details right now (I'm a bit tired), the basic essence is that if the big bang theory is correct, then there
must be a
very specific relationship between all of the above observations. If the observations do not match, then the theory is wrong. But they do match, and with so many independent lines of evidence all converging on the same overall picture, our confidence that that overall picture is correct becomes rather high.
Naturally we are open to modifications of the theory, and many scientists are investigating a wide variety of potential modifications. But the overall picture we can be very certain is correct: that the universe we observe expanded from a very dense (though not infinitely dense) and very smooth hot soup of matter. As it expanded it cooled, first forming the light elements, then emitting the CMB, and then, eventually forming galaxies and galaxy clusters. After the light elements were processed through a series of supernovae within our own galaxy, enough heavy elements had formed for some stars to form rocky planets capable of supporting life. Around one such star with enough heavy elements, the Earth formed, a planet that formed about 9.2 billion years after the initial expansion, on it formed life, and eventually ourselves, some 13.7 billion years or so after the birth of our region of the universe.
All of this is
highly certain, given the evidence we have available to us today.