This is like asking why are there still Jews up to this day when the Jewish
Age has already ended.
We are talking here of spiritual things. The phasing out of the Church Age means that there is no more salvation in religion.
You can no longer subscribe to the Jewish religion and expect to be saved because their heaven has already been closed. That age is already over even if they were successful in building temples because those are nothing to the Father.
It is the same with Christianity. Christians can go on worshipping and doing their own thing, but it does not mean that when they look for their salvation, they will be able to find it because when the Father closes an age, it is forever closed and nobody can open it.
43 Therefore say I unto you, The kingdom of God shall be taken from you, and given to a nation bringing forth the fruits thereof.