God made man very different from the animals.  First of all He made us in His image (Gen 1:26-27), He breathed His own breath into us, giving us life (Gen 2:7), and He gave us each something that no animal has - a spirit (1 Cor 2:11).  Not even the smartest animals on earth, (no matter how much DNA is claimed they have in common with humans) ever prayed to or worshiped anything.  But even the most uncivilized and remote people on earth all had some type of religion.  This is because God made man like this from the beginning, to be spiritual – to know there’s a God, and to seek Him.
Gen 4:26b Then men began to call upon the name of the Lord.”
But most people throughout history have tried to become ‘spiritual’ and in touch with God (or what they believe to be God) through something which can never reach Him: externals.  It’s like building the tower of Babel – trying to get to God by the works of our hands.
Men have created traditions, idols, material representations of every kind, done multitudes of external good works, all to try to meet the call of their spirit – the call to seek and worship God.
Today even many Christian churches have gone down this same path, sincerely believing that the worship of God is found in externals such as: praise music, works to reach the lost, stirring sermons, Bible knowledge, helping the poor, refuting unbelievers, social outreach, etc.
But God has had a different meaning altogether to fulfill this act of ‘worship’ that man has sought for so long, and it goes against our very human nature:  SACRIFICE.  Instead of relying on any tradition, we can see what the Bible’s definition of true spiritual worship is:
Romans 12:1 Therefore I urge you, brethren, by the mercies of God, to present your bodies a living and holy sacrifice, acceptable to God, which is your spiritual service of worship. 2 And do not be conformed to this world, but be transformed by the renewing of your mind, so that you may prove what the will of God is, that which is good and acceptable and perfect.
Animal nature (without God’s Spirit) has always revolved around one thing: self.  The call of God is the opposite.  It goes against human and animal nature (survival of the fittest, living for self).  His call is to present our whole selves as a sacrifice to God – no longer living and working for ourselves.
God made man in 3 parts: body, soul, and spirit.  An unregenerate person will always search to satisfy their body or their soul - seeking food, sleep, sex, companionship, entertainment, fun, happiness – everything for themselves.
A spiritual man or woman is one who lives with the totally opposite motive – to live for God in every aspect.  Their heart is totally different, and that means their motives are totally different.  They seek to do God’s will, and intend on laying down their lives to please God.  It is an internal attitude rather than an external work.  Any external work will flow from that inner attitude of “it’s all about God’s will and what pleases Him.”
One the Pharisees tried to trick Jesus by asking Him (in front of everyone) whether taxes should be paid to Caesar (the hated Roman emperor).  He asked for a coin and said, ‘Whose image is on this coin?’  After they ‘Caesar’s”, He told them “Then give to Caesar what is Caesar’s and to God what is God’s” (Matt 22:21).  That statement is significant because Jesus was saying that “if something has someone’s image, it belongs to them.”  And everyone there knew this one thing: All men and women have been made in the image of God (Genesis 1:27).  So in other words, it was like Jesus was saying “Your focus is on what you can keep for yourself that you think belongs to you, it should be on giving yourself over to God, your Creator, since you belong to Him.”  Our goal in life is to give our Lord everything that belongs to Him – all of the glory, and all of ourselves.  I believe the idea of “Giving ourselves over to God” is just another way of phrasing Romans 12:1 (presenting our bodies as a living sacrifice to God).
This giving all of ourselves over to God is only possible in the New Covenant, because it can only be kept in us with God’s Holy Spirit living in us.  It is no more possible for us to give ourselves over to the Lord without the Holy Spirit, than it is for a deer to willingly lay down in front of a hungry Lion – it can’t do it, it’s not in its nature.  A person needs to die to the old nature of “self” and be “born again” to a new nature, which places the Lord at the center.  Only then can we attain to what billions and billions of people have tried to do in every nation for thousands of years, since the beginning: to truly worship God.  This is what Jesus talked about when He said:
"But an hour is coming, and now is, when the true worshipers will worship the Father in spirit and truth; for such people the Father seeks to be His worshipers.” (John 4:23)
The question I need to ask myself is: am I living like an animal?  Is my motive to gain, gain, gain for myself?  Then I am not worshiping the Lord, and I am not spiritual.  If I have died to my own life and risen to new life in the Spirit which has an aim to live for Him and not for myself, to cleanse myself from anything that’s displeasing to Him, then I can know that I am fulfilling John 4:23 and am a true worshiper.