The saints are presented to believers as role models whose lives are worthy to be imitated.
Heb 6:12: Do not grow lazy, but imitate those who, through faith and patience, are inheriting the promises. (NAB)
Heb 12:1: Therefore, since we for our part are surrounded by this cloud of witnesses, let us lay aside every circumstance of sin which clings to us and persevere in running the race which lies ahead; (NAB)
1 Cor 11:1: Imitate me as I imitate Christ. (NAB)
Phil 3:17: Be imitators of me, my brothers. Take as your guide those who follow the example that we set. (NAB)
Vatican II
For when we look at the lives of those who have faithfully followed Christ, we are inspired with a new reason for seeking the city which is to come (Heb 13:14; 11:10). At the same time, we are shown a most safe path by which … we will be able to arrive at perfect union with Christ, that is holiness. In the lives of those who shared in our humanity and yet were transformed into especially successfully images of Christ (2 Cor 3:18), God vividly manifests to men his presence and his face. He speaks to us in them, and gives us a sign of his kingdom, to which we are powerfully drawn, surrounded as we are by so many witnesses (Heb 12:1), and having such an argument for the truth of the gospel. (Lumen Gentium, 50)
The catechism speaks of the communion of the Church of heaven and earth in Section 954.
954 The three states of the Church. “When the Lord comes in glory, and all his angels with him, death will be no more and all things will be subject to him. But at the present time some of his disciples are pilgrims on earth. Others have died and are being purified, while still others are in glory, contemplating ‘in full light, God himself triune and one, exactly as he is”‘ (Lumen Gentium 49, MT 25:31; 1 Cor 15:26-27; Council of Florence (1439): DS 1305.)
In other words, we have the Church Militant on earth, the Church Suffering in purgatory, and the Church Triumphant in heaven.
955 “So it is that the union of the wayfarers with the brethren who sleep in the peace of Christ is in no way interrupted, but on the contrary, according to the constant faith of the Church, this union is reinforced by an exchange of spiritual goods” (Lumen Gentium 49).
Praying to the Saints/Praying for the Dead
Christians from the earliest centuries of the Church have expressed their communion with those who have died by praying for the dead.
Inscriptions in the Roman catacombs indicate that the early Christians honored and prayed for their deceased relatives and friends.
It is not uncommon that non-believers see the Roman Catholic devotion to the Saints and the dead in general as falling under the prohibition of necrology as found in the Hebrew Scriptures. These people are not aware of the New Life of the Christian who has been called out of this life. They are nor dead, but alive!
Rom 6:1: Are you not aware that we who are baptized into Christ Jesus were baptized into his death? Through baptism into his death we were buried with him, so that just as Christ was raised from the dead by the glory of the Father, we too might live a new life … (NAB)
Col 2:12: In baptism you were not only buried with him but also raised to life with him because you believed in the power of God who raised him from the dead. (NAB)
The early Christians, in praying for their dead were expressing their belief that departed brothers and sisters underwent a purification after death (“purgatory”). Their prayers were prayers that God would have mercy on them during this time of healing and purification.
Many people who do not share the Catholic Christian faith life have difficulty with the appearance that in their prayers, Catholics appear to pray to the Saints, to Mary, as one prays to God. This “praying to” appears to them to indicate a worship of the Saint as if giving to the Saint or Mary what is due to God alone.
However, earliest Christianity has always defined prayer as conversation, as in conversation with God. Conversation, as any other act of communication (e.g., talking, conversation, yelling, etc.), requires a sign of the direction of the communication: one talks to someone, communicates with someone, prays to someone, converses with someone, yells at someone, etc. Hence, praying to God, a Saint, the Virgin Mary indicates simply the direction of prayer communication. It is more a matter of grammar and understanding communication than acknowledging the worship of the receiver.
From the earliest of Church Councils (the Council of Rome, 993; defined by the Council of Trent) the distinction was made between worship and honor. Catholics believe that worship is due to God alone. Catholics honor those saints who have gone before us as a sign of faith and victory in living the Christian life.