Romans 5:12, 15, 17-21 / Luke 6:12-18
The number 1 can have a few interpretations.
In terms of ranking and position, to be number 1 means to be at the top and the first.
But in terms of quantity, then the number 1 is the least and the smallest.
Though the number 1 is the lowest in terms of quantity, it does not necessary mean that its effect or influence can be ignored or discounted.
As it is, one little light can dispel the darkness, and one small spark can set a whole forest on fire.
The 1st reading says that sin entered the world through one man, and through sin, death and thus death has spread through the whole human race because everyone has sinned.
That was the devastating power of the sin of just one man. And if the whole human race have sinned, the devastation can be difficult to comprehend.
But just as the effect of the sin of one man can have devastating consequences, the good act of one man brings everyone life and makes them justified.
That one man is Jesus Christ who made the sacrifice on the Cross and in doing so achieved our salvation.
And united with Jesus Christ, we are never alone or just being the only one facing the troubles and evils of life.
When we unite ourselves with the sacrifice of Jesus on that one Cross, then the number 1 can make a whole big difference.