Don’t confuse culture and gradual inculturation with purity of religion and validity of liturgy.

In the age of the Messiah the faithful are truly drawn “from every nation, from all tribes and peoples and languages”. If your wife would go to any (decent) Catholic or Orthodox church, and learns to "read" the building and the liturgy of Holy Mass, maybe she could recognize the contours of the “pure” or “more Jewish" religion she is yearning for. She could go to modern or more traditional Latin/Greek/Ukrainian/Syriac/Ethiopian/... rites and in the plurality of all those different cultures and temperaments recognize over and over again the exact same elements and basic plan, organically evolved yet meticulously preserved in a chain of unbroken sacramental obedience.

Entering the church building she’d gradually walk from the holy water near the entrance, through the “outer courtyard” for the lay people, to the sanctuary with the sacrificial altar, golden vessels and incense, elevated and separated by altar rail or curtain. Behind is the tabernacle, the Holy of Holies containing the Real Presence, indicated by a lit candle. And if she was to e.g. carefully analyse the words of the Eucharistic prayers in all these different rites and languages, she would find over and over again the same underlying structure, complete with the Haggadah.

But language and cultural differences aside, there must be fundamental differences as well. It is Christ Himself who took the prescribed liturgy of the ancient Passover meal and gave it its full and final meaning by substituting Himself, in the presence of the apostles, for the merely symbolic lamb. It is through Christ that the Trinity is fully revealed.

How then could e.g. the exact same holidays have been retained? For instance, why would you celebrate Shavuot, if with Pentecost the Holy Spirit directly descended on the Church? Another example: the Lord's Day is not "Sabbath on the wrong day". Sabbath laws do not apply to those under the New Covenant. Beyond the most excellent idea of dedicating an entire day to the Lord with plenty of obligatory prayer, rest, food and family/community time, the Christian Sunday is simply not the Sabbath. On Sunday we celebrate the Resurrection, which occurred on the first day of a new week (the supernatural "eighth day", beyond the natural fullness of the old week).

The priest in this age is also no longer a Levite. To properly offer this sacrifice, he is now sacramentally ordained by proper religious authorities “in the Order of Melchizedek”, reminiscent of the royal priesthood of David and the priesthood of Adam and the firstborns. And where the old liturgy was a sign of divine grace, the liturgy of our age is an effective cause of divine grace. If the priest obeys the liturgy that has been prescribed for his own rite and his own day, no amount of personal corruption can take away the sanctity of his work. This also means that there is no fundamental need for wars in the Holy Land or for "conquering" the Temple Mount by force. The Temple is already being built. Every time the faithful, after having been sacramentally cleansed of mortal sin through baptism or confession, participate in the Lord’s sacrifice by eating the body and drinking the blood of the Lamb, they themselves will inevitably become more and more the dwelling place of the Lord within the material creation.