…Catholics offer Mass and perform rituals for the dead?

Catholic are taught that they can help in relieving the sufferings of the departed who souls are in the so-called purgatory by offering mass and performing rituals for them:

“2. The faithful on earth, through the communion saints, can relieve the sufferings of the souls in purgatory by prayer, fasting, and other good works, by indulgences , and by having masses offered for them.”(Louis La Ravoire Marrow, D.D. My Catholic Faith. P. 243)

HOWEVER, EVEN CATHOLIC priest admit that the bible does not mention of a realm such as purgatory. Offering prayers and other sacrifices for the dead is against the teachings of the bible, for the dead have no share in anything that the living do:

“ Now here in the scriptures does the word ‘purgatory’ occur…”(Josseph Kenny, C.S.S.R. Purgatory: A Doctrine of comfort and Hope. p .2)

“For the living know that they will die;but the dead know nothing, and they have no more reward , for the memory of them is forgotten. Also their love, their hatred , and their envy have now perished; nevermore will they have a share in anything done under the sun.”(Eccl. 9:5-6,NKJV)