Perhaps I'm jumping ahead.
So when evening had come, the master of the vineyard said to his steward, 'Call the laborers and give them their wages, beginning from the last to the first.'
And when those came who were hired about the eleventh hour, everyone received a denarius each.
But when the first came, they supposed that they would receive more; and they likewise received a denarius each.
And when they had received it, they murmured against the landowner,
saying, 'These last have worked only one hour, and you have made them equal to us who have endured the burden and heat of the day.'
But he responded to one of them and said, 'Friend, I am doing you no wrong. Did you not agree with me for a denarius?
Take what is yours, and go your way. I desire to give to the last, the same as you.
Is it not lawful for me to do what I want with my own things? Is your eye corrupt because I am good?'
So the last will be first, and the first last. Because many are called, but few are chosen. -Matt 20:8-16
This parable seems grossly unfair. Is not God Just?, we ask. But the parable is in reference to salvation, as the last line indicates. Jesus uses hyperbole, even shocking hyperbole, at times to drive His point deep. Salvation is a gift, wholly undeserved, wholly unmerited. Our attitude should be thankfulness for being Saved at all, and our attention should not be on how well others seem to be doing or on feeling that the sins we were forgiven of are less serious than theirs, so we are more worthy.
1Cor 3 goes on to tell us that there are indeed a variety of Kingdom rewards for obedience. And elsewhere Paul talks about varying degrees of glory. God is not unfair, nor unjust. But Jesus is making the foundational point that our proper attitude should be one of humility and thankfulness for what He gives each of us, not on comparison to others.