“These people honor Me with their lips, but their hearts are far from Me. Their worship is a farce, for they teach man-made ideas as commands from God.” (Matthew 15:8-9, N.L.T.)
The Bible speaks of many different people praying to many different gods. Here are a few examples:
- The Jews from the Old Testament and the Christians from the New Testament prayed to the “LORD” (Yahweh, Jehovah).
- The false prophets of Elijah’s day prayed to Baal.
- The Philistines prayed to Dagon.
- The Moabites prayed to their false gods.
- The people of Ur prayed to their false gods.
- The Egyptians prayed to a pantheon of false gods.
- The book of Jonah says of Jonah’s fellow sailors “and every man cried out to his god.”
All of this praying to all of these various gods proves how naturally religious humans are. You see, innately, we understand that creation’s mere existence proves that there must be a Creator God (Romans 1:20; Psalm 14:1; Psalm 53:1). Since nothing will continue to be nothing endlessly, a creation, especially one as intricately designed and detailed as ours, can’t just burst forth from nothing. Therefore, the fact that we have a creation at all proves that there must be a Creator God. As the old line goes, you can’t have a clock without a clock builder.
From time immemorial, this commonsense fact has driven people to attempt to worship the Creator God and offer up prayers to Him. But the problem has historically been that man’s nature of sin has corrupted these attempts at worship and prayer. Whereas the human race started out with a knowledge of the one true God and how to worship Him, idolatry ultimately became a staple of the race in the wake of Adam and Eve’s sin (Romans 1:20-23).
And so, in the midst of all the praying that is done to all the gods via all the religions, we are left to figure out who is praying legitimate prayers to the legitimate God. Someone says, “Well, I think that any prayer that is prayed in sincerity to any god must be classified as legitimate.” Certainly that idea sounds very sweet in an “I’m okay, you’re okay” kind of way, but it simply isn’t Biblical. Much to the contrary, the Bible says that sacrifices, and by implication prayers, that are offered to idols are, in actuality, offered to demons (fallen angels, the spirits associated with the idols). You’ll find that teaching in 1 Corinthians 10:19-21, Deuteronomy 32:15-18, and Revelation 9:20. Obviously, then, such prayers are a far cry from being legitimate!
Of course, now that God the Son (Jesus) has left heaven, been born to the virgin Mary, lived 33 sinless years upon the earth, evidenced His divinity by way of His miracles, left us with His teachings, died on the cross as the potential payment for the sins of every individual, resurrected, ascended back to heaven, and is now seated at the right hand of God the Father, there is no question what legitimate praying sounds like. It is praying done to God the Father, by way of the High Priestly intercessory ministry of Jesus, in the name of Jesus. And what all is involved with praying in Jesus’ name? To authentically pray in Jesus’ name, you must believe in Jesus as your personal Savior, pray the type of prayers that He would pray, and submit to God the Father’s will in regards to your prayer requests. The fact is, anything less than that, and you get into the realm of illegitimate praying.
The Disciple's Road 
Is it sinful to have religious imagery? Are all religious images idols, even if they depict a scene from the Old or New Testament and even if I don’t pray to them? I have met people who say that having an image of Jesus is like having an image of the hindu god siva or vishnu or krishna. Should I then get rid of my Moses holding the ten commandments wallpaper? Should I then get rid of my Last Supper painting or my Nativity set? Should I then get rid of my cherubim ceramic? But those same people try to justify the cherubim on the ark of the covenant. Isn’t that a catch 22?
In Numbers 21:4-9 the Lord instructs the people of Israel to make a bronze serpent and look to it for healing from their bite wounds. As you pointed out, the lid of the Ark of the Covenant featured a cherub angel depiction on each end, with the tips of the angels’ wings coming together and touching over the top of the middle of the lid. Likewise, 1st Kings 7:23-39 tells us that in the courtyard of Solomon’s temple stood a huge circular bronze basin that held approximately 12,000 gallons of water. This basin stood on representations of twelve oxen (three oxen looking in each direction). These three examples show us that the second commandment (Exodus 20:4-6) doesn’t completely outlaw the use of any and all religious depictions. Obviously, the commandment is primarily meant as a prohibition against man-made false idols and graven images.
However, with this understood, I’m always a little leery of Biblical pictures, paintings, statues, etc. because they create false images in our minds. For example, the average person today has a mental picture of Jesus that comes more from Renaissance artists than the Bible. Did Jesus have long hair? 1st Corinthians 11:14 suggests that He didn’t. Was He good looking? Isaiah 53:2 probably means that He wasn’t. Was He effeminate? That seems hard to believe considering that He was a carpenter who spent most of life outdoors and endured the worst beating the Romans could inflict upon Him before crucifying Him. You see my point. Frankly, I’m even a little cautious about watching Bible-based movies on the life of Jesus. How many such movies truly give an accurate portrayal of Him? Most likely none. So, to answer your question, I wouldn’t automatically say that God commands you to throw all of your “religious” depictions into the trash, but I would certainly limit the esteem in which I held them. Can God use religious artwork in His service? Yes. But is He pleased with all religious artwork? No.