Counterspell is cast as a reaction, so you can cast it normally after casting shield of faith.
That is also why you can coutnerspell a counterspell (despite having obviously cast a different spell in the first place)
And fighter levels for action surge slow down your spell progression, that is a pretty high cost, and sure, for that, you can sometimes cast two spells, but you only have one action surge per short rest, so not reliably, and not always. It has pros and cons.
Allowing everybody to cast multiple leveled spells in a turn just buffs casters, and they already are stronger than martials in 5e.
From Sage Advice Nov 2020, page 15:
“Can you cast a reaction spell on your turn? You sure can! Here’s a common way for it to happen: Cornelius the wizard is casting fireball on his turn, and his foe casts counterspell on him. Cornelius also has counterspell prepared, so he uses his reaction to cast it and break his foe’s counterspell before it can stop fireball.”
