It does not say all Jews, Israelites, Hebrews or any other sect, religion, people groups or anything of that sort, nor does it say all “christians”. It says and Yehovah means “ALL MANKIND” that would join with Him and guard (obey) His Commandments!
Also note that although you are indeed saved by grace alone, your “works” matter and will be judged, (Faith / belief without Works is dead). The scriptures tell you what works He is looking at/for. Torah is the “works” He expects of you! Don’t believe me, research it in the only scriptures available to all “mankind” 2000 years ago. The Tanach which is better known as the “Old Testament”.
Torah is often translated in english as law. Yet it is better translated from the hebrew as instructions. So His Torah is His instructions to His children, His chosen. His elect! So if you are not guarding to do all His instructions, which are easy to do, you are not doing His will.
If Yehovah disciplined the Hebrews during the time of Moses, what makes you thing He won’t discipline you? He disciplines those He loves! And remember, Yehovah is not man nor does He change. He is the same yesterday, same today and the same tomorrow.
Mankind / Man = G444 (Strong)
From G435 and ὤψ ōps (the countenance; from G3700); manfaced, that is, a human being: – certain, man.
May this bless you!