There’s a world of difference between ‘knowledge’ and ‘understanding’.
For one, knowledge is essentially just a worldly thing, while understanding is a pathway or steps along a pathway to one’s spiritual source.
Often, when one acquires knowledge, the begin to think themself better than others. However, gaining understanding only leads one to greater humility and empathy.
Ironically, however, knowledge is much more ‘easily’ gained. All one has to do is fill their head with information and they gain knowledge. Gaining understanding requires a deep effort to look into the root of things, or, actually, in most cases is just a pure gift.
Whereas knowledge may lead one to hate others (others of a different religion, society, political group, profession, etc.), understanding leads one to forgiving, accepting, and even sometimes welcoming those who differ from you.
To close, understanding is a key part of spiritual development, while knowledge is not really a spiritual issue at all. While knowledge is fine to accumulate, and can help one in worldly matters, there are many things to watch out for as one accumulates knowledge.
And here is a nice quote from the Sufi Hazrat Inayat Khan to further illustrate some of the points above:
“The Sufi looks on all with tolerance, and knows that there is a path for everyone. The path of the lover is for him, the path of the one seeking for wealth is for him, the seeker after paradise is following his path, it is all a journey…. Let each choose the way that belongs to his own temperament and tendency…. The saying of Buddha, ‘Forgive all’, comes true. Forgiveness does not come by learning, it comes by understanding that a person should be allowed to travel along that path which is suited to his temperament. As long as he is journeying with open eyes, let him journey….”
Of course, there is relative truth and there is absolute Truth, and Inayat Khan, presumably in touch with or very close to absolute Truth, does not neglect to point that out:
“The great thing is that one should journey with one single desire. There should be the single desire: whether to love a beloved, to collect wealth, or to do some good for the world of humanity, or to attain paradise. There should be the desire to journey to the goal. So many do not know which is the goal or what it is. One thinks wealth is the goal, another paradise, another the beloved. They do not see that there is still a further goal. They are naturally prompted by the desire to get to the goal, and yet they are not conscious of the further goal.
“As it is said in the Bible: ‘Seek ye first the kingdom of God, and all things shall be added unto you.’”
When it comes to others, it is ideal to be accepting of any path they choose. However, when it comes to ourselves, we should really look to identify what the most useful, most important, highest path is. And, in words, always inadequate for this topic, that is to ‘seek the kingdom of God’….