It has not been a problem at all for me CG, in Fact it was the Bible that aided me in seeing the Message of Baha'u'llah and the Message of Baha'u'llah confirmed to me how relevant the Bible was. The Bible is a key in accepting the return spoken of by all the Prophets of the Old Testament and by Jesus and His Disciples, I see it all happened as promised and it is still happening as the Bible says it will.
Learning basic maths in early schooling does not become irrelevant in later learning, it becomes a firm foundation.
I have mentioned many many times to you the two aspects of Faith, the part that does not change and the part that does. Links to read about it posted also many times. As you keep bringing this up it appears you did not read, nor consider the explanations posted. Thus in all fairness, I see there is no need to repeat. You can look it up anytime, if you in your futures yoy see the need to.
The answer to the changing aspect of all faiths lays in the most basic Truth given by God unto us, which is;
God does, what God chooses. Thus the new Message is the New Heaven and the new Earth promised in Scriptures. It is a new Creation to which all things are made new.
Regards Tony