>>619090
>>619140
Not sure how to address all of those since I'm not sure what you mean about the conception of law between Judaism and Catholicism (unless you're meaning is the old testament 'Judaism'? Because Christianity and modern Talmudic parsing really couldn't be more different), but the ones I can:
>The validity of some of the Catholic/Orthodox doctrines/dogmas like Marian devotion, the use of icons/statues
This really comes down to authority, I'm sure there's been much theology trying to arrive at Marian devotion from first principles or directly from scripture, but even being a Catholic I don't find such arguments very convincing. the bottom line is that Christ built the church and imbued it with Divine authority; they have the authority in declaring spiritual practice valid or invalid. All arguments about such differences in ritual practice ultimately rest on you accepting their authority. If you wish to determine if their authority is genuine through examining practice, I believe this is impossible. Mother Church has often been mistaken, but can never relinquish authority in scriptural interpretation. I may agree much more with a Southern baptist about sodomy than I would the average Jesuit, but the fact remains that one can administer valid sacraments and one cannot.
>The doctrine of the Trinity
This is one which I feel has been fairly effectively tackled both from first principles and from scripture, but I couldn't do those arguments justice, you'd do best to look up the abundance of Catholic writings on the subject. (Pleb summary: a perfectly loving God requires three persons, because simple 'self-love', which would be necessary of a Unitarian God pre-creation, is imperfect).
>The impotence of Christianity
Are you speaking politically, militarily, socially?
In any case, historically the strength of Christianity has often peaked and waned, this isn't the first moment in history where people feared that the faith was dying, and won't be the last, but we've outlasted them all.
Also I know this may be a wasted effort, but in case you're considering Christianity in contrast to (God forbid) islam or paganism, my favorite argument would be to look at each one as a predictive system of humanity; do you really believe the phsychological models that islam or any other religion have of the human being are nearly so accurate or profound as Christianity's? Assuming you can recognize that, surely it's against the odds that this is just the sum of the folk wisdom of the backward nomads that were the Israelites (as shown in there hurry to worship a golden bull when left to their own devices, lol). As well just consider their end times prophesies, does it strike you as more likely that anti-christ will eventually hold power over all the world, or will the entirety of Earth be converted to Islam where we will live in a war free utopia? Universal evil upon earth is terrifying, universal happiness upon earth is absurd.