Maybe that's because this is what you've been taught by your church hierarchy -- do as we say and don't question it.
But the funny thing is I didn't find your definition of "partial" as you presented it at dictionary.com.
Imagine that.
Dictionary.com Unbridged biased or prejudiced in favor of a person, group, side
But you didn't finished that sentence. Surprisingly, you left off half the definition...
"biased or prejudiced in favor of a person, group, side, etc., over another, as in a controversy: a partial witness.
So "partial" is a good thing. Just as Christ is a very partial witness for those who are His.
For emphasis, dictionary.com adds...
"Favoring one person or side over another or others; biased or prejudiced: a decision that was partial to the plaintiff."
So again we see that to be "partial towards someone," even under the rubric of "bias and prejudice," is still a good thing for those who have been so favored.
(Interestingly, also note the judicial context of both examples. Exactly like Scripture and God's perfect judgment of His children by the acquittal won for them by Christ on the cross.)
Further, I didn't find words like "unfair" or "unjust" to define "partial." Those words were used, however, under "Related Forms" for the word "partialness."
Not quite the same thing...
Related forms
par·tial·ly, adverb
par·tial·ness, noun
"Synonyms 1. unfinished, imperfect, limited. 2. one-sided, unfair, unjust.
As you can see, this is referring to a different word -- partialness.
The fact remains that to be "partial" toward someone means to favor them, as God has favored His children by redeeming them from their sins through the blood of Christ.
How does one experience true gratitude if one does not rightly understand God's gift of unmerited grace?
"Herein is love, not that we loved God, but that He loved us, and sent his Son to be the propitiation for our sins." -- 1 John 4:10
I think he’s not used to dealing with scripture educated Bereans
Really? Your own link seems to prove you wrong.
But you didn't finished that sentence. Surprisingly, you left off half the definition... biased or prejudiced in favor of a person, group, side, etc., over another, as in a controversy: a partial witness
Well, you conveniently left out the synonyms and antonyms on the same page. Imagine that!
—Synonyms 1. unfinished, imperfect, limited. 2. one-sided, unfair, unjust
So "partial" is a good thing
Yeah? Which part? Unfinished? Imperfect? Limited? One-sided? Unfair? Unjust?
If you were on trial and you discovered that the judge is partial would that put to at ease? If you found out that the jury is partial, would you claim that justice is served? If a witness was believed to be partial would you say that is good? Do you not know what impartial means? The Antonyms of partial are:
—Antonyms 1, 3. complete. 2. unbiased, fair.
Which do you think is closer to God? Unfinished, imperfect, limited, one-sided, unfair, unjust OR complete, perfect, unbiased, fair?
We were speaking of God as a Perfect Judge, not of 1000 silverings' chicken dumplings she is extremely partial to (by her own admission). I don't want my Judge to be partial, but just—equally to all.
You, on the other hand, want none of impartiality but someone who will be on your side no matter how guilty you may be. Partiality and equal justice for all is mutually exclusive.
The more I think of what you are saying the more it seems to me that Protestantism may favor prejudice as something "good." And, that is a very disturbing realization.