My dear, the Old Testament was never just the Torah. The Torah is only a small section of the Old Testament... Only 5 books out of 39 (or 46 for Catholics) the Torah we have now is the same Torah that was given to Moses and was the same Torah that was in use at the time of your Prophet. The New Testament was not sent to "agree" with the Old Testament but to fulfil its message. The New Testament contains some teachings of the Old Testament because those teachings are for mankind for all time, like the Ten Commandments that God gave to Moses.Assallamu alaikim brother Peter:
We (muslems) believe that the Old Testament is not exactly the Torah that was sent to prophet Musa alaihi alsalam ( peace be upon him), . It was changed by old people . Still there is agreement between Old Testament, New Testament and Quran in some parts, which I believe all from Allah subhanahu wa taaala.
I suggest that we concentrate on the islamic creed and morality . Islamic laws need some skill in tafseer, knoweldge of hadith and very good in arabic ( by the way not any arabic person have good skill in arabic : arabic should be studied ) , I think we should examine the opinions of the scholars concerning islamic Laws and see for ourselves.
Islamic creed gives logical correct answers to big questions humanity have. Islam put sincere pure faith in our creator. Islam make our personality quiet , stable, thankful, patient , peaceful and sincere by knowing Allah and his beautiful names ( the one who created us). When light and love of Allah settle in our hearts our attitude towards all that is around us will be balanced . This need a good practice by prayers ,( sincere ones).
So you can give good advice about Islam because this is what you know, but it is not good practice to say the Bible is changed or corrupted without evidence to prove it is. This implies God would not protect His word from His creation which is very wrong and illogical. It's not enough to say that bits of the Bible (that doesn't agree with Qur'an) is changed but the rest is ok. You need to look at what is different and what are the consequences to Gods original revelations in the previous scriptures and the difference these make to mankind. That is what I have been doing in my time here. It's been an interesting journey of discovery.
Peace to you... Btw, you may not know much about Biblical scripture but I do think your knowledge of Islam is excellent and your patience and kindness in answering questions is always apparent. Keep doing what you do best. Keep God in your heart.