THOU gave me wisdom, even though I am a child or THOU gave me wisdom even though I am a child. Should I put comma before the even though?
In your case, you don't need a comma before even though.
There is never a comma between an independent clause (complete sentence) and a subordinate (or dependent) clause.
However, if the subordinate clause comes before the complete sentence, use a comma after it. (source 1, source 2)
In your example, thou gave me wisdom is a complete sentence, and even though I am a child is a subordinate clause.
You have two options:
Thou gave me wisdom even though I am a child.
Even though I am a child, thou gave me wisdom.
When I was in high school, our English teacher taught us that a comma represents a pause, which caused untold confusion for the students. The students ended up sprinkling commas throughout their writings like salt on eggs! Every time they stopped to take a breath or decide how they wanted to continue, they paused and dutifully added a comma. Since becoming an advanced-level grammar teacher I have discovered from a variety of grammar texts that commas are more about the mechanics of constructing a sentence than the writer needing or wanting to "pause". I agree with the first answer about not separating a main clause from a subordinate(adverb)clause, so no comma is used. Only if the subordinate clause precedes the main clause does it have a comma between the two clauses: I went to work even though I felt sick. Even though I felt sick, I went to work.
The general rule for subordinating conjunctions states that you shouldn't use a comma before a subordinating conjunction that comes after the main clause. However, "whereas" and "although" are examples of adverbs of concession, along with "though" and "even though". They are used where a dependent clause is contrasting to the main clause (a bit like "but").