Brit native, not a teacher
I have read your post but it doesn't say what is is you want. Do you want each sentence to be corrected where necessary or for someone to choose the best formulation, or something else?
The first thing I notice is that there is a mistake in the slang line: "Leading as straight a life as he can". The second thing I notice is that this contains the idea of trying to live a good life "as straight a life as he can". In the rewritten examples the concept of endeavouring to has been replaced with simply doing. Therefore in sentence 2 I would say "2. A man should try to lead an honest life and contribute his share to the common cause.
Sentence 3 is a lot stronger than the original. "Leading as straight a life as one can" is a lot less onerous a task than "not deviating from the path of righteousness".
I would tend to use oblivious to rather than oblivious of, but I believe both are correct.
Student or Learner