Its not so much idol worship that people have images of loved ones that have departed. But what they do with them?
What is the purpose?
Its like the teaching according to the parable. A tool for teaching the disicples to how walk by faith (hear God not seen) after the unseen eternal. . rather than what the eyes see the temporal
Its not what goes into a man that can defile them which includes the things we see. But what comes out.
Matthew 15:19-2o King James Do not ye yet understand, that whatsoever entereth in at the mouth goeth into the belly, and is cast out into the draught? But those things which proceed out of the mouth come forth from the heart; and they defile the man.For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies:These are the things which defile a man: but to eat with unwashen hands defileth not a man.
As a object lesson using his own flesh as a a parable many time after teaching a parable he himself would disappear or hide so the unseen Spirit could do its work.
Matthew 15:21 Then Jesus went thence, and departed into the coasts of Tyre and Sidon.
In Mathew as a object lesson or parable He uses two blind men to emphasize the work of his ministry .In so much he came to give the spiritual blind eyes to see, and the spiritual deaf ears to hear what the Spirit says to the churches (everyone who has ears to hear.) .
Matthew 9:26-28 King James Version (KJV)And the fame hereof went abroad into all that land. And when Jesus departed thence, two blind men followed him, crying, and saying, Thou son of David, have mercy on us.And when he was come into the house, the blind men came to him: and Jesus saith unto them, Believe ye that I am able to do this? They said unto him, Yea, Lord.
One more example of using flesh to demonstrate the unseen as in now you see hIm ...now you do not.
But he is still there working in the hearts the disciples like that of Peter . Peter one of disciples who did not walk away because they had no faith .The gospel offended them as a hard saying. They stopped up the ears and refused to believe in a God not seen
Many therefore of his disciples, when they had heard this, said, This is an hard saying; (offensive) who can hear it? When Jesus knew in himself that his disciples murmured at it, he said unto them, Doth this offend you? What and if ye shall see the Son of man ascend up where he was before? It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life But there are some of you that believe not. (no faith) For Jesus knew from the beginning who they were that believed not, and who should betray him.And he said, Therefore said I unto you, that no man can come unto me, except it were given unto him of my Father. From that time many of his disciples went back, and walked(beleived in him) no more with him.Then said Jesus unto the twelve, Will ye also go away? Then Simon Peter answered him, Lord, to whom shall we go? thou hast the words (not flesh) of eternal life. John 6: 60-68