God consciousness means to be conscious of God. To be conscious of God, knowledge of God is required. Most religions have as a tenet that one must love God.
However, to love God, one must know God, and few religions have little or no information on God. The Abrahamic religions, for instance, have only very rudimentary information to offer on God - God is the creator, God is great, and God defines good and evil. When it comes to who God is, what He looks like, and what He does for fun, that knowledge is absent in these religions.
Christianity has as a main instruction to love God with all thy heart, but how can you love a person, you don’t even know what looks like, or what He likes to do?
The first question asked of any person in a new relationship, is - what do you like to do? What are your interests?
To love someone, to have a relationship with someone, clearly one must know that person. It is not possible to give all your love to an unknown person, so when the Church directs you to love God with all your heart, it may sound good, and well meaning, but it is not at all tenable.
You can be God conscious only by knowing who God is. To know that God is the creator, or the greatest, or the judge, is not much to go on, in order to know who God is.
The only religion on the planet that offers knowledge of God, knowledge which is not based on mere faith, but which is documented by the largest and most ancient body of knowledge known to mankind - The Vedas, is the Vaishnava religion.
If a person honestly want to know God, he must approach Krishna. Krishna is not only the oldest version of God, He is also the only version of God, who tells you who He really is.
In other words - to be God conscious, by definition, means to be Krishna conscious.
Just ask a Christian or a Muslim, what it means to be Jahve- or Allah conscious, and you’ll will know what I am talking about.
Now hear, O son of Prtha, how by practicing yoga in full consciousness of Me, with mind attached to Me, you can know Me in full, free from doubt.
I shall now declare unto you in full this knowledge, both phenomenal and numinous. This being known, nothing further shall remain for you to know.
Out of many thousands among men, one may endeavor for perfection, and of those who have achieved perfection, hardly one knows Me in truth.
Earth, water, fire, air, ether, mind, intelligence and false ego -- all together these eight constitute My separated material energies.
Besides these, O mighty-armed Arjuna, there is another, superior energy of Mine, which comprises the living entities who are exploiting the resources of this material, inferior nature.
All created beings have their source in these two natures. Of all that is material and all that is spiritual in this world, know for certain that I am both the origin and the dissolution.
O conqueror of wealth, there is no truth superior to Me. Everything rests upon Me, as pearls are strung on a thread.
--Bhagavad Gita 7.1-7