David Clarkson writes of the "twofold worship due only to God, internal and external."
External worship is the religious activity - bowing, and I suppose singing, reciting, and whatever else goes along with a religious service.
Internal worship, as Clarkson says, is "the acts of the soul and actions answerable thereto."
When the mind is most taken up with an object, and the heart and affections most set upon it, this is soul worship, and this is due only to God. For He being the chief good, and the last end of intelligent creatures, it is his due, proper to him alone, to be most minded and most affected; it is the hour due only to the Lord to have the first, the highest place, both in our minds and hearts and endeavors.
Therein, external idolatry is something like bowing to an idol. But secret and soul idolatry is
when the mind and heart is set upon anything more than God; when anything is more valued, more intended; anything more trusted, more loved, or our endeavors more for any other thing than God.
Clarkson chillingly concludes:
Secret idolaters shall have no inheritance in the kingdom of God.
Every thought, attitude, word and deed is one of worship. The worship is either true - devoted to the God of the Bible - or false - devoted to anything else. This is paramount for all of life and specifically for counseling. Our problems of the soul, our relationships, and our outlook are so often problems of lingering soul idolatry.