In 1 Corinthians 13, what is meant by the phrase "..thinketh no evil,.." and how does that relate to Biblical charity?

Your question concerns the last phrase in 1 Corinthians 13:5Doth not behave itself unseemly, seeketh not her own, is not easily provoked, thinketh no evil;
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1 Corinthians 13:4Charity suffereth long, and is kind; charity envieth not; charity vaunteth not itself, is not puffed up,
See All... Charity suffereth long, and is kind; charity envieth not; charity vaunteth not itself, is not puffed up, 5 Doth not behave itself unseemly, seeketh not her own, is not easily provoked, thinketh no evil;

When Christ forgave the sins of the man sick of the palsy, we read in Matthew 9:3-4 [3] And, behold, certain of the scribes said within themselves, This man blasphemeth. [4] And Jesus knowing their thoughts said, Wherefore think ye evil in your hearts?
See All..., "And, behold, certain of the scribes said within themselves, This man blasphemeth. And Jesus knowing their thoughts said, Wherefore think ye evil in your hearts?" Here, they thought evil (bad) thoughts about Jesus Christ. They thought that He blasphemed because he told a man that his sins were forgiven.

But charity, according to our scripture, does not think evil of those who are benefactors of that charity. If you love another with the love of charity, you will not assign evil motives to their actions. Rather, you will seek to find an innocent motive for what they have done. And, when they have done wrong, you will not think of the wrong they have done, but of the care that you have for them.

1 Peter 4:8And above all things have fervent charity among yourselves: for charity shall cover the multitude of sins.
See All... states, "And above all things have fervent charity among yourselves: for charity shall cover the multitude of sins." Charity will cover a multitude of sins. That is, you will cover over their sins and accept them despite these sins because of charity. You will not repeat their sin to others. You will not hold their sin against them. Your charity refuses to think evil of them. Proverbs 17:9He that covereth a transgression seeketh love; but he that repeateth a matter separateth very friends.
See All... states, "He that covereth a transgression seeketh love; but he that repeateth a matter separateth very friends." This is the work of charity.

No wonder then, that according to 2 Peter 1:7And to godliness brotherly kindness; and to brotherly kindness charity.
See All..., charity is the height of Christian maturity and one step past brotherly kindness. No wonder also that it is called the "bond of perfectness" (Colossians 3:14And above all these things put on charity, which is the bond of perfectness.
See All...). And, no wonder that in the trinity of the Christian virtues mentioned in 1 Corinthians 13:13And now abideth faith, hope, charity, these three; but the greatest of these is charity.
See All... (faith, hope, charity), it is the greatest of the three. May we all grow in this greatest of Christian graces.