The NT fully affirms all that is written in the OT.
The Koran makes the claim that previous revelations are corrupt and thus contradicts them.
Your comparison of the NT succession to the OT and the Koran succession to the NT/OT hasn't been thoughtful.
Are you saying then that, for instance, all the appointed times - Sabbaths and feasts - are affirmed in the NT? Will you be observing Pesach, Sukkot, or even Chanukah this year as Y'shua did? Will you be spending Sabbaths in the synagogue as was Y'shua's custom and as Jacob/James enjoined new proselytes to do - so as to learn Moses (Acts 15)?