“Not to mention” Vs. “Let alone” [duplicate]

Bothe of these phrases seem to express and depict the same meaning.

• As I can remember, John was kind-hearted and tolerant; let alone, he was a man of God.

• As I can remember, John was Kind-hearted and tolerant; not to mention, he was a man of God.

How to use and differentiate between them?

Dictionary:

not to mention:

In addition to or as well as what's been discussed; used for adding a comment that emphasizes the main idea of what you have already said.

Let alone:

used for saying that something is even less likely to happen than another unlikely thing; used to emphasize that something is more impossible than another thing:

Solution 1:

I wouldn't write either of those examples in exactly that way. They both sound wrong to this native Oregonian.

Generally I go for the simplest wording that communicates the point. Your message is more powerful when you use fewer words and shorter sentences.

I would write it like this:

John was kind-hearted and tolerant. He was a man of God.

Some specifics:

• "As I can remember" doesn't really say anything. Everything you write is "as you can remember". So we can remove it.
• "let alone" or "not to mention" are often just filler. "not to mention" can sometimes be used to good effect because of its irony: whenever you say "not to mention", it means that you are about to mention the thing that you said "not to mention". This can be fun when used sparingly. But if you can say the same thing in a more straightforward way, that is usually a better option.
• If you do use "not to mention", it's probably better to word it something like "not to mention that he was a man of God" instead of "not to mention, he was a man of God." But really I would just avoid that phrasing here.

When in doubt, keep it simple. Use short and direct sentences. Get right to the point.