“...Bring no more vain oblations;...etc.”
The key word here is VAIN - the new oblations are not VAIN because all things are new in Christ. Isaiah does not say bring no more oblations - he says bring no more VAIN ones. Without Christ they remain vain, when done in Christ and following HIS example these things are no longer vain (i.e., without merit). Do you get it? This is about understanding what the bible is truly saying, not extra biblical.
Matthew 6:7 But when ye pray, use not vain repetitions, as the heathen do: for they think that they shall be heard for their much speaking.