The opposite of “seeking first the kingdom of Jesus Christ” can very often be seeking first our ease and pleasure in life.
When avoiding at all cost discomfort or disadvantage (as compared to our neighbors) occupies much of our thought lives, and prayer lives. Even while doing churchy or religious things.
Much of Christianity today is in the business of promoting and justifying this self-seeking way of thinking.
Teachers think and teach that since “Jesus is for me, and not against me” so it must be ok for me to also be all about and for me.
Jesus is for me yes but he’s not for all of me. He’s not for what Paul called “the old man”. The part of me that is fallen and selfish and that is destined for death.
He is for the new man in me, the man of the ecclesia that is united to Christ and seated with him in heavenly places.
There is part of the Christian that needs to die daily. To not get his/her way in life. To be disciplined and actually be destroyed.
That human fallen side to us, God is not for him, he is in fact AGAINST that guy. And that guy is part of every one of us.
There is another part of a Christian that is an overcomer. That is seated with Christ high above the heavens. That does love and is part of a community of believers. That man/woman does need to be public and reach out and display Jesus Christ together with others and individually.