Look at it this way…The kingdom of God is created inside of us. It grows as we continue to walk obediently to God’s law. The more obedient we are, the more the kingdom is able to grow inside of us and the more sin (or desire to sin) is purged from within us. The greater the kingdom, the weaker the desire to sin. As you walk as a Christian your body literally becomes the temple of Christ. When it is complete Jesus will come and live inside of you. This is truth. If you read your bible you will see it for yourself. I didn’t make this stuff up.
When God says seek ye first the kingdom. He’s saying this because a man/woman cannot live righteously (resisting sin) until the kingdom inside of him/her is somewhat developed. Like I said, the greater the kingdom is inside of you, the less garbage (desire to sin) is inside of you. This is the best I’m able to explain this now.

Also, accepting Jesus as your saviour is the way to salvation. It’s not complicated. We aren’t required to understand the mysteries of God and the Bible to receive it. For some, their calling is simple, as having the faith of a child with no understanding, merely believing. For others not so.
There are mysteries in life that can be revealed by reading the Bible…but, until God allows us to see, we are blind, even to the little things.
God bless,
Sheheryar izhar you.