Sounds like a dwarf cleric to me. You fight well into the structure of the religious hierarchy, and you are like to debate theology. It would probably be a war god, maybe a life god or something else physical.
Given the explicit "I am atheist," that might not be the best choice.
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Personally,
@GoblinOrc I think this describes
either a Bladesinger Wizard (a Wizard who fights) or an Eldritch Knight Fighter (a warrior who does magic things.) Overall, you sound somewhere between TN and LN; you are "rebellious" (a very Chaotic trait), but you are also Logical, Loyal, Disciplined (working out regularly), and prefer "structured environments." Plus, you seem committed to keeping your promises even if it costs you a lot to do so--"my word is my bond" is a pretty Lawful thing. This seems, on balance, to lean in a Lawful direction but could be Neutral. Your argumentativeness, ambition, and being difficult to get along with implies a lean away from Good, but nothing Evil, hence I favor Neutrality on that axis: not going out of your way to be nice/kind/supportive, but not
avoiding being those things, either.
Your difficulty getting along with others, and your emphasis on logic/intellect and physical strength, inclines me away from Warlock, since the closest fit there would seem to be Blade Pact, which generally wants to dump Strength, and
all Warlocks want to have high Charisma.
Overall, I think Eldritch Knight makes the most sense if you want to be a pure single-class character. Alternatively, you could do 1-2 levels of Fighter, and then take Wizard thereafter; a Fighter 2/Wizard N is quite potent, and can leverage either Evoker (for raw spell output) or Diviner (for support/debuff benefits) quite well while still going in for melee. Keep in mind, Action Surge lets you cast two actual spells in the same round--a lot of people misremember the casting limitations, the actual rule is "you can't cast a levelled spell
as a bonus action unless all other spells you cast that round are cantrips with a casting time of 1 action."
Sadly, an emphasis on Strength makes the greatest combo (Fighter 2/Bladesinger Wizard) largely a non-starter. You'd want to dump Strength and focus on Dexterity, which doesn't suit the description you've given here.