"and a poor chap would stand considerable show with the widow's Providence." Chap.3 P. 15 What's the meaning of "considerable show" in this?
Here, Huck is comparing/contrasting Miss Watson's version of Providence (heaven and religion) with the Widow's. It's one of the many instances when Huck is confronted with hypocrisy in society, and attempts to make some kind of sense from it. What he's saying here is that a poor man would be able to enter the Widow's version of heaven, but not Miss Watson's. "Considerable show" essentially means that the poor man would have a chance to enter heaven in the Widow's mind. But with Miss Watson, there's such a sense of show and circumstance surrounding religion that the average person doesn't stand a chance.
This is one of Huck's first encounters with the duality of adult society. He finds 2 versions of religion, even in the same household. It leads him to believe that perhaps there is no "right" idea of heaven; everyone must decide their own faith. He finds this hypocrisy reflected in nearly every aspect of society in his travels, and this is one of the first times he's exposed to the reality of human nature.