Contradiction with John 15:2
While Luke 13:9 suggests giving the tree another chance after additional care, John 15:2 states that unfruitful branches are taken away without mention of a second chance.
John 15:2: Every branch in me that beareth not fruit he taketh away: and every [branch] that beareth fruit, he purgeth it, that it may bring forth more fruit.
Contradiction with Matthew 21:19
Luke 13:9 allows for possible redemption of the tree with future results, whereas Matthew 21:19 depicts the immediate cursing and withering of an unfruitful fig tree.
Matthew 21:19: And when he saw a fig tree in the way, he came to it, and found nothing thereon, but leaves only, and said unto it, Let no fruit grow on thee henceforward for ever. And presently the fig tree withered away. [a fig tree: Gr. one fig tree]
Contradiction with Hebrews 6:8
In contrast to the potential reprieve in Luke 13:9, Hebrews 6:8 describes a land that bears thorns as being near to curse and burning.
Hebrews 6:8: But that which beareth thorns and briers [is] rejected, and [is] nigh unto cursing; whose end [is] to be burned.
Contradiction with Matthew 7:19
While Luke 13:9 offers a final opportunity for fruitfulness, Matthew 7:19 states that every tree not producing good fruit is uniformly hewn down and cast into the fire.
Matthew 7:19: Every tree that bringeth not forth good fruit is hewn down, and cast into the fire.
Contradiction with Isaiah 5:5-6
Luke 13:9 offers hope with another year's care, whereas Isaiah 5:5-6 describes the vineyard’s hedge being removed due to lack of fruit, resulting in its desolation.
Isaiah 5:5-6: And now go to; I will tell you what I will do to my vineyard: I will take away the hedge thereof, and it shall be eaten up; [and] break down the wall thereof, and it shall be trodden down: [trodden...: Heb. for a treading]