Romans 14:9
For to this end Christ died and lived again, that He might be Lord both of the dead and of the living.
Non-Catholics sometimes ask what the difference is between the Catholic habit of prayer to the blessed dead and necromancy or seance. In reply, the Catholic asks, "What is the difference between miracles and magic? Or between the biblical prophecy and clairvoyance?" Answer those questions and you've answered the question about prayer to the dead. For the basic difference in all three questions is Jesus Christ. Prayer to and for the dead is not done despite Jesus but through Him. He is our sole bond with the blessed dead. But since He lives forever and they live in Him, then they remain bonded to us in Him as well. For we are members, not merely of Christ, but of one another (Rom 12:5). So say a prayer for your beloved dead and ask them to pray for you. And ask the Father to hear all these prayers through Jesus Christ.