A brief personal perspective
Idolatry is the worship of any cult image, idea or object, rather than the worship of God. It is that alternative which makes idolatry so wrong, from a religious point of view.
Idolatry should not be confused with using images, statues and icons as a focus for worshipping God. This is not idolatry but, rather, an aid to prayer. There is a massive difference between using an image in this way and actually worshipping the image itself.
It has been stated that no image could be adequate as a representation of God but this is to misunderstand the use of images; they are not there to represent God but to assist in concentrating the mind upon God.
There may be a danger, when the image looks like a person or an animal1 or when something inanimate is considered, that the image or object itself becomes the focus for desire. However, we must remember that God speaks and acts as a living being; He is not an inanimate object (although an object may be inspirational in reaching out to Him).
It is also worth remembering that idolatry, in and of itself, is wrong because it goes against one of the ten commandments.2 3
What about devotion to Mary, the Mother of Jesus? Again it is vital to appreciate that Mary acts as a focus for devotion. Through the centuries, because of their respect and love for her, Christians have sought the prayers of Mary but these are always to support their petitions to God. This is not idolatry. Similarly, relics are often venerated, that is revered or regarded with great respect: they are not idolised.
So, should religious images and relics have a place in the Church today? I would say yes, as a powerful, tangible aid to assisting in focussed prayer and as an inspiration to help us to work towards becoming more Christ-like. They can also be used to great effect, alongside other items such as stained glass, for educational purposes.
1 Romans 1.23
2 Exodus 20.4-5a: You shall not make for yourself an image in the form of anything in heaven above or on the earth beneath or in the waters below. You shall not bow down to them or worship them.
3 Deuteronomy 5.8-9a: You shall not make for yourself a carved image, or any likeness of anything that is in heaven above, or that is on the earth beneath, or that is in the water under the earth. You shall not bow down to them or serve them.
© Richard Farquharson, Maulden, Bedfordshire April 2016