This post will show that those who reject the prayers to the saints are pagans who have as much to do with Christ and the Bible as Muhammed. Their claims/arguments are presented as headers.
Praying to the saints is paganism. You must only pray to God because only God saves.
There is not a single verse in the Bible stating that one must only pray to God or that prayer implies worship, or that prayers is only directed at those who save. Prayer means to ask. When we pray to God, we are asking Him directly for His aid. When we pray to the saints, we are praying for them to intercede for us and bolster our request to God.
But where in the Bible does Jesus tell us to pray to the saints?
In Matthew 10:16 "Behold, I send you forth as sheep in the midst of wolves: be ye therefore wise as serpents, and harmless as doves."
And of course in all verses commanding christians to be wise, or to develop in virtue, or to be prepared to enter the Kingdom of God. Because those who are wise will seek the powerful prayers of the saints in order to develop in virtue or be helped against evil.
But the saints are dead and can't hear prayers!
Against that is what Scripture says: "For he is not a God of the dead, but of the living: for all live unto him." (Luke 20:38).
Beings in heaven are perfected and are aware of the things that happen on Earth. For example, the angels in Matthew 18:10 ("Take heed that ye despise not one of these little ones; for I say unto you, That in heaven their angels do always behold the face of my Father which is in heaven."). Or the angels in Luke 15:10 ("Likewise, I say unto you, there is joy in the presence of the angels of God over one sinner that repenteth."). And other examples that can be found.
And not only angels. In Luke 16:29 ("Abraham saith unto him, They have Moses and the prophets; let them hear them.") Abraham has knowledge of prophets who lived well after his death.
But they would have to be God to hear all the prayers directed at them!
The perception of the saints is not limited like our bodies. In Revelation 5:13 it is described how John hears the prayers of "...every creature which is in heaven, and on the earth, and under the earth, and such as are in the sea, and all that are in them, heard I saying, Blessing, and honour, and glory, and power, be unto him that sitteth upon the throne, and unto the Lamb for ever and ever."
But intercession is heretical, I am saved by God I don't need people to pray for me, and Jesus is the only mediator!
Against that is what Scripture says: "I exhort therefore, that, first of all, supplications, prayers, intercessions, and giving of thanks, be made for all men;" (1 Timothy 2:1). Furthermore, the Holy Spirit is also described as intercessor in Romans 8:26 ("Likewise the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered."). The mediation of Jesus is unrelated to intercession or prayer overall, since otherwise all the former verses would be contradictory. Jesus is not a prayer delivery man, and even in such nonsensical logic, that would apply to prayers to God, while these are prayers to saints.
But the prayers of the saints have no power, God doesn't need them nor cares about them!
Against that is what Scripture says: "Then another angel, who had a golden censer, came and stood at the altar. He was given much incense to offer, along with the prayers of all the saints, on the golden altar before the throne. And the smoke of the incense, together with the prayers of the saints, rose up before God from the hand of the angel." (Revelation 8:3-4) and "when he had taken the book, the four beasts and four and twenty elders fell down before the Lamb, having every one of them harps, and golden vials full of odours, which are the prayers of saints." (Revelation 5:8).
But there is no instance of anyone praying to the saints in the Bible so it is not Biblical.
There is also no instance of anyone praying explicitely, separatedly to the Holy Spirit in the Bible. There are also no instances in the Bible of 99% of the typical customs and structures followed by the average pagan that cries about the prayers to the saints.
What is Biblical are not things that appear verbatim on the Bible but things that are consistent with the Bible and a result of its correct understanding. Therefore as has been seen in the former sections, not praying to the saints is unbiblical.
But can't I just pray to God directly?
God already knows your heart, so if we were to follow some kind of prayer minimalism, there is no need to pray at all since we do not tell God anything He doesn't know. God wants to give power to the saints, so their intercession adds to our prayer just like the intercession of any other person. The prayers have different purposes, so one does not make the other less useful, just like people ask others to pray for them instead of "just asking God directly".
Conclusions
Whoever rejects the prayers to the saints believes in a God of the dead and that sainthood limits people to less than they have on Earth, even to the point of being deaf and and of no further interest to God. They reject the commands regarding intercession and the clear way in which saints are given power.
Therefore, whoever wants to be biblical, as in, consistent with the Bible and following the practices it promotes and encourages, must recognize the virtue of praying to the saints.