I think we need to pause here a minute.
The preposition generally used and translated 'for' in the relevant passages is
huper, which means 'on behalf of.' as in Galatians 2:20 and 3:13. for example Now if I buy pay a bill on your behalf (not likely to happen!), I pay it and you don't. If Christ suffers on our behalf, He suffers and we don't. That is substitution and if a penalty is involved, it is penal substitution. Let's look at Galatians 3:13.
Christ has redeemed us from the curse of the law, having become a curse for [Gk.
huper] us.' He becomes a curse and we don't. That's penal substitution.
There are some places where the preposition
anti is used. It tends to mean 'over against' or 'instead of.' Luke 11:11.
'...Will he for [Gk.
anti. 'instead of'']
a fish give him a serpent?' Now look at Mark 10:45 or Matthew 20:28.
'.....And give His life a ransom for [Gk.
anti]
many.' The ransom is paid to God's justice. Christ pays it; we don't. Penal Substitution.
There are several other Greek prepositions translated 'for' but I think these two are the most important.