Critics reject the Catholic doctrine of praying to the saints as they claimed that if the saints could hear the prayers of those who are still on earth then that would indicate that they too are omniscent like God Himself. They further propose that the departed are neither aware of the prayers of the faithful nor can hear them. So how can it be possible?
The historic practice of asking the departed brothers and sisters in Christ—the saints—for their intercession came in existence during the apostolic era and even before the incarnation of the Son of God. Hence, the true Christian Church strongly believes that the saints are very much aware of the prayers of those still on earth as testified by St. John the Apostle, “And when he had taken the scroll, the four living creatures and the twenty-four elders fell down before the Lamb, each holding a harp, and with golden bowls full of incense, which are the prayers of the saints” (Revelation 5:8; see also Revelation 8:3-4). These biblical passages clearly indicate that if the saints are offering prayers to the Most High then that would only mean that they too are aware of them. Simply, logical. This is further proven by the very words of the Lord Jesus Christ when He said that the guardian angels of the little children are always with the Father and would intercede on behalf of them, “See that you do not despise one of these little ones; for I tell you that in heaven their angels always behold the face of my Father who is in heaven” (Matthew 18:10). See? Undoubtedly, they know.
Moreover, the saints are not omniscent and will never be omniscent. The Holy Catholic Church never ever define any doctrine of the omniscence of those whom she declares to be in heaven. However, she teaches that, in their perfection, they are enjoying the beatific vision of God, and thus seeing in God all of the knowledge they need that is relevant to them including the prayers of the faithful. St. Paul said, “For [now] we know in part … but when perfection comes, the imperfect disappears. When I was a child, I talked like a child, I thought like a child, I reasoned like a child. When I became a man, I put childish ways behind me. Now we see but a poor reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known” (1 Corinthians 13:9-12). By which, the saints become even more knowledgeable than those who are still living on earth.
As the Holy Church infallibly speaks: “Those who die in God’s grace and friendship and are perfectly purified live for ever with Christ. They are like God for ever, for they ‘see him as he is,’ face to face” (CCC 1023).