The teaching of the Catholic Church is that our departed brothers and sisters in Christ reign in heaven with God, who is a god of the living (cf. Matthew 22:32), and therefore enjoy an especially close relationship with him. This does not deny that Christians still combating their way through the trials of this world are saints (from the Latin for holy, sanctus), because we are children of God even now. But in the new life, we will be like God:
Beloved, we are God's children now; it does not yet appear what we shall be, but we know that when he appears we shall be like him, for we shall see him as he is. (1 John 3)In heaven, we will reach the fullness of the image of God.
For now we see in a mirror dimly, but then face to face. (1 Cor 13)
The saints are to God like stained glass is to sunlight. Light from the sun is white, but when passed through a prism or colored glass, it's constitution becomes evident: the many colors that combine to form its radiance dance varied hues and textures to reveal the hidden perfections of the original light beam. So it is with the saints. Their lives and their faith show the perfections of God's holiness shining through our human weakness. By contemplating and honoring their goodness, we come better to know and revere the overawing holiness of God.
And we desire each one of you to show the same earnestness in realizing the full assurance of hope until the end, so that you may not be sluggish, but imitators of those who through faith and patience inherit the promises. (Hebrews 6:11-12)
Be imitators of me, as I am of Christ. (1 Cor 11:1, cf. 1 Cor 4:16)
Only God should be worshipped. Yet, we should also honor those to whom honor is due. It is not that God alone should be honored; instead, it is far more honorable to God to praise him as excelling the greatness of something great, that to praise him as better than nothingness. When you praise a child in front of its parents, they do not take offense. Rather they take your praise of their child as a complement. Similarly, every time we praise excellence in a creature, we implicitly praise the Creator who has brought forth such goodness.
The Church calls the worship of God latria and distinguishes it from dulia, the reverence due the saints.
Calling to mind the virtues of the saints helps us to appreciate better God's all-encompassing goodness. It easy to fail to appreciate the infinity of the sky, but we more easily appreciate it when we compare our smallness to a towering mountain or to a cloud sailing low overhead and then realize that the sky looms farther above than we can imagine.
Acts 19:12 relics of saints Hebrews 12:1 cloud of witnesses
Rest assured, the only image that Catholics worship is Jesus Christ. He is ``the image of the invisible God'' (Col 1:15), for ``in him the whole fullness of deity dwells bodily'' (Col 2:9).
The worship of images of the saints is condemned by the Catholic Church. The idea dating back to beginnings of Christianity is that there is more to the Church than we see here on earth: all believers, living and dead, form one family. Having the images of holy men and women in churches is like carrying the photograph of a loved one; such an image helps to call to mind the person and one's love for them.
The veneration of images is not a violation of the First Commandment. The Catechism of the Catholic Church points out:
2129 The divine injunction included the prohibition of every representation of God by the hand of man. Deuteronomy explains: "Since you saw no form on the day that the Lord spoke to you at Horeb out of the midst of the fire, beware lest you act corruptly by making a graven image for yourselves, in the form of any figure...." It is the absolutely transcendent God who revealed himself to Israel. "He is the all," but at the same time "he is greater than all his works." He is "the author of beauty."
2130 Nevertheless, already in the Old Testament, God ordained or permitted the making of images that pointed symbolically toward salvation by the incarnate Word: so it was with the bronze serpent, the ark of the covenant, and the cherubim.
2131 Basing itself on the mystery of the incarnate Word, the seventh ecumenical council at Nicaea (787) [see below] justified against the iconoclasts the veneration of icons - of Christ, but also of the Mother of God, the angels, and all the saints. By becoming incarnate, the Son of God introduced a new "economy" of images.
2132 The Christian veneration of images is not contrary to the first commandment which proscribes idols. Indeed, "the honor rendered to an image passes to its prototype," and "whoever venerates an image venerates the person portrayed in it." The honor paid to sacred images is a "respectful veneration," not the adoration due to God alone: Religious worship is not directed to images in themselves, considered as mere things, but under their distinctive aspect as images leading us on to God incarnate. The movement toward the image does not terminate in it as image, but tends toward that whose image it is.
The practice of keeping in Churches the images of saints dates back to the earliest days of Christianity. The practice was so widespread that it only became an issue in the eighth century, when a group known as iconoclasts rose to declare veneration of images idolatrous. The seventh ecumenical council (council of all bishops) of the Church held in Nicea in 787 A.D. was organized to refute the opponents of icons:
To summarize, we declare that we defend free from any innovations all the written and unwritten ecclesiastical traditions that have been entrusted to us. One of these is the production of representational art; this is quite in harmony with the history of the spread of the gospel, as it provides confirmation that the becoming man of the Word of God was real and not just imaginary, and as it brings us a similar benefit. For, things that mutually illustrate one another undoubtedly possess one another's message.
Given this state of affairs and stepping out as though on the royal highway, following as we are the God-spoken teaching of our holy fathers and the tradition of the catholic church--for we recognize that this tradition comes from the holy Spirit who dwells in her-- we decree with full precision and care that, like the figure of the honoured and life-giving cross, the revered and holy images, whether painted or made of mosaic or of other suitable material, are to be exposed in the holy churches of God, on sacred instruments and vestments, on walls and panels, in houses and by public ways; these are the images of our Lord, God and saviour, Jesus Christ, and of our Lady without blemish, the holy God-bearer, and of the revered angels and of any of the saintly holy men. The more frequently they are seen in representational art, the more are those who see them are drawn to remember and long for those who serve as models, and to pay these images the tribute of salutation and respectful veneration. Certainly this is not the full adoration in accordance with our faith, which is properly paid only to the divine nature, but it resembles that given to the figure of the honored and life-giving cross, and also to the holy books of the gospels and to other sacred cult objects. Further, people are drawn to honor these images with the offering of incense and lights, as was piously established by ancient custom. Indeed the honor paid to an image traverses it, reaching the model; and he who venerates the image, venerates the person represented in that image. (pp. 135-7)
The council condemned the opponents of images, specifically
Often, perhaps when life is troubling us, we'll ask a relative or close friend to pray for us. It is very good that we do ask people to pray for us and our needs and also to pray for them. Praying to the saints is like asking your friend to pray for you. You still pray to Jesus, but your friend is praying with you. Not only does prayer help benefit the receiver, but also the person who prays: it draws us all into closer union with Christ and with each other.
The saints are our fellow Christians who have died in God's favor, and now stand before God face to face, in the closest union with him. God is well pleased with them, and so, like a doting grandparent, he is especially willing to grant their petitions.
When we here on earth have recourse to the saints by praying to them, we are merely asking them to ask God for us. The use of the word `pray' might put off some people here, but when we pray to the saints, we are not praying to them as to God. This use of `pray' is similar to the older use of the word as in `praying to the court' to mean petitioning the court.
But the souls of the righteous are in the hand of God, and no torment will ever touch them. In the eyes of the foolish they seemed to have died, and their departure was thought to be an affliction, and their going from us to be their destruction; but they are at peace. For though in the sight of men they were punished, their hope is full of immortality. Having been disciplined a little, they will receive great good, because God tested them and found them worthy of himself; like gold in the furnace he tried them, and like a sacrificial burnt offering he accepted them. In the time of their visitation they will shine forth, and will run like sparks through the stubble. They will govern nations and rule over peoples, and the Lord will reign over them for ever. Those who trust in him will understand truth, and the faithful will abide with him in love, because grace and mercy are upon his elect, and he watches over his holy ones.
Wisdom 3:1-9 (cf. Daniel 12:1-3)
Recalling the victory of the saints is a great encouragement for us Christians still combating our way throught the trials of this world. Thomas Howard recalls an evangelical hymn `Art thou weary, art thou languid' from his youth:
After speaking for six exquisite verses about the difficulties of following Jesus, the hymn concludes, ``Finding following keeping struggling/Is he sure to bless?/Angels, prophets, martyrs, virgins/Answer, Yes.'' I was overwhelmed by this picture. What solace! What encouragement! I was in an ancient lineage, and all of these forerunners knew everything I had experienced, and all of them could testify, ``Keep going! It is worth it! Praise God!''
Howard, Thomas. Evangelical Is Not Enough: Worship of God In Liturgy and Sacrament. Ignatius, San Francisco, 1984, p. 58.