Dought & clear, - Definition of riba and ruling on work that helps with riba

What is the definition of riba? If we take into account the fact that
in most countries the economy is based on the principle of the
circulation of capital, which includes lending, is accepting payment
in that particular currency for any work regarded as an action that
supports the riba-based system ? Is using the currency of a state that
is based on riba regarded as contributing to the usurious economy?
Undoubtedly the employee in a riba-based bank plays a part in
riba-based transactions one way or another, even if he is a security
guard for the bank. Could you offer him a better job if you have
anything to offer?
Praise be to Allah.
Riba means an increase in a particular item. The word is derived from
a root meaning increase or growth. Allah, may He be exalted, says
(interpretation of the meaning): "Whatever you pay as interest so that
it may increase (li yarbu) the wealth of people does not increase (fa
la yarbu) in the sight of Allah" [ar-Room 30:39]., i.e., it does not
increase or rise in status before Allah.
Riba originated among the people of the Jaahiliyyah; if a debt became
due, they would say to him (the borrower): Give us one hundred (that
is due, now), or increase it to one hundred and fifty (and pay later).
Then when the one hundred and fifty became due, they would say: Give
us one hundred and fifty (now), or increase it to two hundred (and pay
later) -- and so on.
Islam also forbade another kind of riba, namely riba al-fadl, which
means adding to the amount when exchanging one item for another of the
same type. So if gold is sold for gold, that is not permissible except
like for like, hand to hand. Islam stipulated that the exchange should
be done hand to hand and that the items or goods should be of the same
quality. Whoever gives more or asks for more has engaged in riba. If
he sells a saa' of wheat for two saa's (of the same commodity), even
if it is hand to hand, he has engaged in riba.
The principle of the circulation of capital exists in both the Muslim
world and the non-Muslim world. What it means is circulating capital
so that it will increase. The same applies to lending; they give money
as a loan provided that it will increase when they get it back. Such
transactions are undoubtedly riba.
There is nothing wrong with the principle of the circulation of
capital if the capital is invested in trade or business, and the
profit is shared between the owner of the capital and the worker. This
is called mudaarabah (profit sharing), and there is nothing wrong with
it if the capital is kept distinct from the profit. If this money is
deposited in a riba-based bank, then taking the interest is haraam and
it is not permissible to consume it. It is not permissible to deal
with these banks, and loans based on interest are not permissible. It
is also not permissible to accept payment in that currency for any job
if that job helps to support a system that is based on riba.
With regard to using this currency (such as the dollar), there is
nothing wrong with doing so in the case of necessity, even if that
leads to helping to advance the economy of that country. That is
because the dollar is accepted in most Muslim and other countries, so
it is permissible to deal with it because of necessity. But if there
is an Islamic currency that is used, then we can do away with the
dollar.
And Allah knows best.