Are you disputing the observation that "life exists". Is it your position that the assumption that life exists is flawed? Are you even listening to yourself? At some point in Earth's history, life "came to be here". Evolution has nothing to say about that, other than SOMEHOW a god, alien, chemistry, or some other as of yet undiscovered cause made life. the HYPOTHESIS of abiogenisis is nothing you will get a strong argument over... it is not a scientific theory because we do not know enough yet.. no one you should ever trust for scientific knowledge has ever said that.
What we do know is that life comes from life. Life does not spring from non-life (although some people imagine that it could). That leaves God or aliens as the source of life on earth.
...neither of which actually answers the question at all.
Either life can come from non-life - whether here, or on another planet is not particularly relevant - or it cannot.
If it cannot, then life must have always existed.
The conditions in the vast majority of the universe, for the vast majority of time, are inimical to life. There is good reason to think that life has not always existed. There is no good reason to think that life has always existed.
'God' doesn't help; if life cannot come from non-life, then any putative 'God' must be alive. The simplest life needs few resources; and we know that few resources existed to support life prior to the formation of the solar system - so the parsimonious hypothesis would be the eternal existence of some kind of simple bacterium; or better still a virus. A massively powerful, and eternal life-form simply isn't a sane hypothesis - in order for such a thing to have existed, most of modern science would have to be completely wrong - but if it were, then simple experiments would have different results from those we observe.
By far the best explanation - and by best, I mean the explanation that would require the fewest changes to established science, in order to fit into the framework of our current knowledge - is that life did indeed come from non-living precursors.
The eternal existence of life (or indeed, of anything) is a seriously poor hypothesis - but it is necessary if we are to accept the premise that "Life does not spring from non-life".
If the premise is true, then the whole of science - not just biology, but physics and chemistry too - is wrong. And wrong in a huge way, but in a way that is simultaneously so subtle as to be undetectable. That is as close to impossible as an idea gets.
If the premise is false, then that implies some interesting things - such as that 'life' is not a special 'non-physical' trait, but is simply an emergent property of some arrangements of atoms. Of course, if that were the case, then it would be hard to define what is and is not 'alive' when looking at objects that fall close to the boundary between the two states. For example, we might see debate about whether viruses are alive or not, with no clear or compelling argument for either outcome - and indeed, that is exactly what does happen.
The idea that life can arise from non-life - albeit rarely - fits neatly into the framework of knowledge we have built over centuries about how things are. The idea that it cannot would require the whole of science to be massively wrong, but in a so far undetected way. Accepting a premise that contradicts a wide swath of known facts is the very definition of stupidity.
I don't imagine that life could spring from non-life; on the contrary, I can see that imagining that it cannot would be monumentally dumb.
