"For as in one body we have many members, and not all the members have the same function, so we, who are many, are one body in Christ, and individually we are members one of another." - Romans 12:4-5
Here, Paul unmistakably says that we are all connected. Not only are we all members of the body of Christ, but we are also all members OF EACH OTHER! This bond between Christians is the core of the Communion of Saints; once we realize this, we have the basis of the whole doctrine.
"But as it is, God arranged the members in the body, each one of them, as he chose. If all were a single member, where would the body be? As it is, there are many members, yet one body. The eye cannot say to the hand, 'I have no need of you', nor again the head to the feet, 'I have no need of you.'" - 1 Corinthians 12:18-21
The various members of the body of Christ NEED each other; we cannot say that since a Christian has died, we no longer need him.
"Pray in the Spirit at all times in every prayer and supplication. To that end keep alert and always persevere in supplication for all the saints." - Ephesians 6:18
"First of all, then, I urge that supplications, prayers, intercessions, and thanksgivings should be made for everyone" - 1 Timothy 2:1
In these two verses, Paul exhorts us to pray for one another. Intercessory prayer is just one way that we, as the members of the body of Christ, help each other. While he was talking specifically about the Church on earth, there's no reason why those in heaven cannot intercede for those on earth. In fact, Scripture tells us that those in heaven DO intercede for us.
"Then the LORD said to me: Though Moses and Samuel stood before me, yet my heart would not turn towards this people. Send them out of my sight, and let them go!" - Jeremiah 15:1
"When he had taken the scroll, the four living creatures and the twenty-four elders fell before the Lamb, each holding a harp and golden bowls full of incense, which are the prayers of the saints*." - Revelation 5:8
"Another angel with a golden censer came and stood at the altar; he was given a great quantity of incense to offer with the prayers of all the saints* on the golden altar that is before the throne. And the smoke of the incense, with the prayers of the saints*, rose before God from the hand of the angel." - Revelation 8:3-4
In these three passages we see saints (including angels) interceding for us and offering our prayers to God. This is EXPLICIT evidence for their intercession. One may argue that the prayers they are offering weren't directed towards them, but this just digs the hole deeper. It is nonsense to say that they can hear us when we pray directly to God, but we can't ask for their intercession.
* - When Scripture uses the term "saints," it is referring to Christians on earth, not those in heaven.
"For there is one God; there is also one mediator between God and humankind, Christ Jesus" - 1 Timothy 2:5
A common Protestant objection to the Communion of saints goes something like this: "By asking saints in heaven to pray for us, you make them mediators between you and God, but only Jesus is a mediator." By that logic, anybody interceding for anyone else would be usurping Christ's role as mediator, which is absurd.
So, what does it mean that Christ is the one mediator? First, He is the mediator of the New Covenant. Secondly, He is the mediator because He is the only Person who is both God and man.
"No one shall be found among you who makes a son or daughter pass through fire, or who practices divination, or is a soothsayer, or an augur, or a sorcerer, or one who casts spells, or who consults ghosts or spirits, or who seeks oracles from the dead." - Deuteronomy 18:10-11
Another common Protestant objection is that by praying to the saints, we are consulting the dead, which is forbidden by Scripture. However, this is a misunderstanding of what it means to consult the dead. To consult the dead means to conjure them (as in a s�ance) and seek information from them, which is totally different from asking them to pray for us. It's a false comparison.
"I am the LORD your God, who brought you out of the land of Egypt, out of the house of slavery; you shall have no other gods before me." - Exodus 20:2-3
Some Protestants object that by praying to and venerating the saints, we are worshipping them, but this simply isn't true. First of all, when we pray to the saints, it's not the same type of prayer directed towards God. We don't adore them; we merely ask for their intercession. Secondly, we don't worship them when we venerate them, either. We merely honor them in the same way we would honor someone on earth who saved someone's life or did some other heroic deed. I will go deeper into this subject in the next section.
A fourth common Protestant objection is the objection that saints in heaven cannot hear all the prayers directed towards them. The problem with this argument is that the saints in heaven are outside of time, so they are not limited in being able to answer prayers as we are.
Many Protestants object that by honoring the saints, we are taking glory away from God. But is this really true? Let me give an example. Does a magnificent palace and beautiful decor take away from the glory of a king? Or would he be more glorious if he banned anything beautiful in his kingdom except for himself. The first king obviously has more glory, and it's the same way with God. It actually brings him more glory when His creatures and His kingdom are honored.
But, Protestants object, many of the ways in which we honor saints resembles worship more than mere veneration. Is this argument legitimate? Let's take a look at what Scripture says.
"Let peoples serve you [referring to Jacob], and nations bow down to you. Be lord over your brothers, and may your mother's sons bow down to you." - Genesis 27:29
"Judah, your brothers shall praise you; your hand shall be on the neck of your enemies; your father's sons shall bow down before you." - Genesis 49:8
"Elisha summoned Gehazi and said, 'Call the Shunammite woman.' So he called her. When she came to him, he said, 'Take your son.' She came and fell at his feet, bowing to the ground; then she took her son and left." - 2 Kings 4:36-37
These are just three examples of people bowing down to and honoring others WITHOUT worshipping them, but they are sufficient to show that there IS a difference between worship and veneration.
So, why do we honor the saints? In the three Scripture passages I gave, Jacob, Judah, and Elisha are all honored, so why shouldn't we honor people also? The same argument can be given with modern-day heroes. We honor people such as Martin Luther King, so why can't we honor the saints? As I have shown, they can hear us when we ask them to intercede for us, so why wouldn't they be able to hear us when we praise them?
Why do Catholics venerate relics (remains of saints and objects that they touched during their lives) and images of saints? Isn't this idolatry? Let's see what Scripture has to say about this subject.
First, let's look at relics from a common sense point of view. We have relics because they're reminders of the saints, just like someone may carry their deceased grandfather's license in their wallet.
Secondly, let's see what Scripture says about the power of relics.
"So Elisha died, and they buried him. Now bands of Moabites used to invade the land in the spring of the year. As a man was being buried, a marauding band was seen and the man was thrown into the grave of Elisha; as soon as the man touched the bones of Elisha, he came to life and stood on his feet." - 2 Kings 13:20-21
"After the people of that place recognized him, they sent word throughout the region and brought all who were sick to him, and begged him that they might touch even the fringe of his cloak; and all who touched it were healed." - Matthew 14:35-36
"Yet more than ever believers were added to the Lord, great numbers of both men and women, so that they even carried out the sick into the streets, and laid them on cots and mats, in order that Peter's shadow might fall on some of them as he came by." - Acts 5:14-15
"God did extraordinary miracles through Paul, so that when the handkerchiefs or aprons that had touched his skin were brought to the sick, their diseases left them, and the evil spirits came out of them." - Acts 19:11-12
All of these passages testify to the power of relics, especially the first one. While the other three refer to relics of living people, the first example of Elisha's bones show that God works miracles even through the relics of the dead.
Next, let's look at the veneration of images. Many Protestants say that making statues and icons of Jesus and the saints violates God's command in Exodus 20:4-5 not to make graven images. However, let's take a look at the passage.
"Thou shalt not make to thyself a graven thing, nor the likeness of any thing that is in heaven above, or in the earth beneath, nor of those things that are in the waters under the earth. Thou shalt not adore them, nor serve them" - Exodus 20:4-5 (Douay-Rheims)
If we read the passage closely, we see that God is forbidding images to be worshipped, and Catholics don't worship images. So, we don't violate God's command. However, let's look and see what Scripture says about using images for religious purposes.
"You shall make two cherubim of gold; you shall make them of hammered work, at the two ends of the mercy seat. Make one cherub at the one end, and one cherub at the other; of one piece with the mercy seat you shall make the cherubim at its two ends." - Exodus 25:18-19
"In the inner sanctuary he [Solomon] made two cherubim of olive wood, each ten cubits high." - 1 Kings 6:23
In the first passage, we see that God actually COMMANDS the making of images for the Ark of the Covenant. In the second passage, Solomon puts two cherubim in the temple. It's interesting to note two things:
1) Solomon puts the cherubim in after God tells him to obey His commands (1 Kings 6:11-13)
2) God actually APPROVED of the temple Solomon had made (1 Kings 9:1-3).
Now, granted, these images weren't necessarily venerated, but it does show that it's okay to have them. But is it okay to venerate images? Maybe that's going a bit too far?
When we venerate images, we are honoring the person represented. Since we don't have the saints physically here with us, we venerate their images as symbols of our veneration of them. It must be stressed that when we venerate images, we are not doing it for the sake of the image itself. Rather, we look past the image and see the saint it represents and venerate the saint. While I don't know of any explicit Scriptural passage that tells us to venerate images, Scripture does not condemn the practice, so, if we're allowed to venerate saints (as I have shown that we are), there's no reason why we can't venerate images.