Even if they fail to finish for whatever reason, it's not a bad occupation to have spent time building a church and donating to the cause.
Undoubtedly.
All for the glory of God and the salvation of souls.
Even if it brings just one soul to God - perhaps even that of the donor.
Look at all the glorious churches and monasteries in England desecrated by the Protestants - were they a waste of time?
We shall do our part and leave the outcome to Almighty God, praying that it will be a happy one.