The first law of thermodynamics tells us that the total energy in the universe, or in any isolated part of it, remains constant. In other words, energy (or its mass equivalent) is not now being created or destroyed; it simply changes form. Countless experiments have verified this.
A corollary of the first law is that natural processes cannot create energy. Therefore, energy must have been created in the past by some agency or power outside and independent of the natural universe. Furthermore, if natural processes cannot produce mass and energy (the inorganic portion of the universe) then it is even less likely that natural processes can produce the much more complex organic (or living) portion of the universe.