[The Lumster]

What led Christians to adopt this custom

Because the so called church decided to disregard the clear teaching of scripture and include pagan practices in their worship of God.

Learn not the way of the heathen.......(Jer 10:2)

When thou art come into the land which the LORD thy God giveth thee, thou shalt not learn to do after the abominations of those nations. (Deut 18:9)

[DouglasKC]

Jer 10:2 Thus saith the LORD, Learn not the way of the heathen, and be not dismayed at the signs of heaven; for the heathen are dismayed at them.
Jer 10:3 For the customs of the people are vain: for one cutteth a tree out of the forest, the work of the hands of the workman, with the axe.
Jer 10:4 They deck it with silver and with gold; they fasten it with nails and with hammers, that it move not.
Jer 10:5 They are upright as the palm tree, but speak not: they must needs be borne, because they cannot go. Be not afraid of them; for they cannot do evil, neither also is it in them to do good.
Jer 10:6 Forasmuch as there is none like unto thee, O LORD; thou art great, and thy name is great in might.
Jer 10:7 Who would not fear thee, O King of nations? for to thee doth it appertain: forasmuch as among all the wise men of the nations, and in all their kingdoms, there is none like unto thee.
Jer 10:8 But they are altogether brutish and foolish: the stock is a doctrine of vanities.
Jer 10:9 Silver spread into plates is brought from Tarshish, and gold from Uphaz, the work of the workman, and of the hands of the founder: blue and purple is their clothing: they are all the work of cunning men.
Jer 10:10 But the LORD is the true God, he is the living God, and an everlasting king: at his wrath the earth shall tremble, and the nations shall not be able to abide his indignation.

[Para-Ord.45]

"...for one cutteth a tree out of the forest, the work of the hands of the workman, with the axe. They deck it with silver and with gold; they fasten it with nails and with hammers, that it move not."