In general, subordinating conjunctions become part of the subordinated clause they create, which means the position of the subordinated clause (including the conjunction) in the sentence relative to the other (main) clause can change. Coordinating conjunctions, however, must remain between the two clauses (or whatever elements).
In the case of "for" and "because", any instance of "for" can be replaced (on the surface) with "because" and it will still read properly. But not every instance of "because" can be replaced with "for":
"Because I have a wife of my own, I
cannot marry you."
is fine, while this is not:
"For I have a wife of my own, I cannot marry you."
"For" must always come between the two clauses. [added later: This means it does not form part of the clause that follows it, so there is no subordinate clause; both clauses are independent clauses "coordinated" by the conjunction "for".
"Because", on the other hand, becomes part of the clause, "because I have a wife of my own". That clause cannot stand on its own as a sentence, so we say it is subordinate to the main clause, "I cannot marry you". That means "because" is a subordinating conjunction.
To your examples, these sentences are bad English:
- *"For I have no money, I cannot give you any."
- *"For he worked hard, he deserved to succeed."
- *"For the blessed shall obtain mercy, they are blessed."