Why did God look upon Abel’s offering with favor and not Cain’s?

BECAUSE ABEL OFFERED THE PERFECT WORSHIP – THE GOD-ORDAINED WORSHIP OF “WORSHIPING IN SPIRIT AND IN TRUTH”. 
 
Now to those who are MISLED into believing that worshiping in Spirit is by ‘the manifestation of the spiritual gift of tongues’ are bound to be alarmed by the answer.  Likewise, those misled into believing all sorts of lies concerning the offerings of Cain and Abel will also find themselves suitably ill-disposed to accepting the above revelation.  Unless of course one is committed to learning Truth.  Giving Truth a chance in one’s life is the greatest favor one can do to oneself.
 
Because unraveling the truth has been a constant struggle with the churches for fear of exposure.  So in a bid to keep themselves and their deeds well concealed they have been churning out lies after lies.  There can be no hope for those who follow them.  Read what God’s Word testifies of them, Matt 23:13, “Woe to you, teachers of the law… you hypocrites!  You shut the kingdom of heaven in men’s faces.  You yourselves do not enter, nor will you let those enter who are trying to.” However, for Truth seekers, the good news is His unfailing promise, “…. There is nothing concealed that will not be disclosed, or hidden that will not be made known.” (Matt 10:26).
   
Perfect Worship, the worship that is holy, pleasing and acceptable unto God is the worship that proclaims and honors God.  It is only possible for THOSE WHO KNOW GOD, which again is only possible for those who receive the Truth and abide by it:
 
    1. Now God is Spirit (Jn 4:24).  Which means He has no physical form or rather He is not bound by any physical form.  So first of all when we worship we ought to honor THIS KNOWLEDGE, and as directed in Ex 20:4, we shall not make for ourselves “an idol in the form of anything in heaven above or on the earth beneath or in the waters below.”  We shall not “bow down to them or worship them.”  For in doing so, we DESECRATE HIS HOLY NAME AND PRONOUNCE BLASPHEMIES.
 
    2.  But we are to proclaim His Holy Name by the Truth or the knowledge we have received of Him and FROM HIM (Jn 6:45).  Yes, every act of worship that we perform before Him should be a testimony to the Truth.  They should declare His glory.  They should describe the majesty of His holiness.  And above all they should declare our Salvation, which He paved for us, without which we cannot even assume to enter His Presence and offer our worship in the first place.
 
    3.  We ought not to confuse our supplications with worship.  One thing common to all of us is that when our prayers are answered, we go about assuming that God has looked upon us with favor!  Not quite so!  Where prayers, supplication or cries of distress are concerned, God does hear them and deliver us – whether we are wicked or righteous.  Oh, yes, He sends rain to the wicked and righteous alike (Matt 5:45).  But that is because He is a Compassionate God (Deut 4:31).  “He does not treat us as our sins deserve or repay us according to our iniquities.” (Ps 103:10).  He remembers that we are but dust (Ps 103:14).
 
    Worship on the other hand is “A Sacrifice of Praise”  – of glorifying and thanksgiving (Matt 6:9-10) – the perfect fruit of consecrated lips – lips that confess His Name (Heb 13:15).  (To learn more, read the Commandment to Sacrifice and Crimes of Babylon-II in this website.)
 
Having come to the above understanding, it should become easier for us to truly grasp as to why God looked with favor on Abel and his offering and not on Cain and his offering.  Gen 4:7 will make it clear to us that both Cain and Abel knew the Truth, which means both knew what was the right thing to do.  “Then the Lord said to Cain, ‘Why are you angry?  Why is your face downcast?  If you do what is right, will you not be accepted?  But IF YOU DO NOT DO WHAT IS RIGHT, SIN IS CROUCHING AT YOUR DOOR…” (Gen 4:6-7). 
 
Thus we discover that while Abel brought fat portions from some of the FIRSTBORN of his flock, Cain brought some of the fruits of the soil as offering to God. 
 
So, how did Abel honor God?  And how did Cain dishonor God?  The answer is: Like Abel, Cain also ought to have offered some of the  FIRSTFRUITS of the soil.
 
Why firstborn or firstfruit?  Because it glorifies God by proclaiming the knowledge of Him, of who He is: “The First and the Last, the Beginning and the End.” (Rev 22:13)  It proclaims His Salvation He has wrought through Jesus Christ, His Son, the Firstborn over all creation.
 
For being the Very Image of Himself, the Perfect Revelation of Himself, He was able to offer Himself as the Perfect Sacrifice for the redemption of mankind. For eg. read Col 1:15, “He is the Image of invisible God, the Firstborn over all creation.”
 
He is the Gospel (Gen 3:15), the  Firstfruit of the Seed which is His Word which created all things. This is the reason the Israelites were taught to consecrate and offer their firstborn and firstfruits – whether of man, animal or soil.  Sadly, they on their part, lost the true spiritual insight concerning it and turned to honoring their firstborns instead!!
 
He is the Firstfruit of death, being the only One to have risen from the dead and to live on.  And this is the reason after Jesus fulfilled all these prophecies concerning Himself, we now commemorate His great work of Salvation he wrought for us by the partaking of the Lord’s Table as an act of perfect worship.  Just as Melchizedek did way back (Gen 14:18).  And though the knowledge got corrupted and lost soon after, Jesus was faithful to once again teach and reinstate it on the eve of His holy Sacrifice (Matt 26:26-28). 
 
This is the knowledge that Abel proclaimed by His offering.  Thus he truly honored God and proclaimed the Gospel. His was the perfect thanksgiving offered with perfect humility which comes from absolute submission to God’s Word.  Perhaps there was a lot he had to learn yet.  But he remained true to the little he had received.  And it is only to such as these God reveals more of Himself and of His wonderful deeds, even those which are awaiting fulfillment (eg.Matt 25:29, Prov 1:23 etc.).  The rest follow Cain’s way and are swallowed up by their sins.