About a year ago, I attended a Bible study and the topic was friends and friendship. I had remembered reading a section from the book of Sirach in the Apocrypha and wish I'd had a copy to read to the group, since I feel that although the group I was with (primarily Baptist) do not consider the Apocrypha to be scripture and do not have it in their Bibles. I feel that the Aprorypha is not to be given the same weight as the Old and New Testament, but I feel that it does contain some worthwhile material. One such example is Sirach 6:5-17, which I will now quote, from the NRSV:
[5] Pleasant speech multiplies friends, and a gracious tongue multiplies courtesies.
[6] Let those who are friendly with you be many, but let your advisers be one in a thousand.
[7] When you gain friends, gain them through testing, and do not trust them hastily.
[8] For there are friends who are such when it suits them, but they will not stand by you in time of trouble.
[9] And there are friends who change into enemies, and tell of the quarrel to your disgrace.
[10] And there are friends who sit at your table, but they will not stand by you in time of trouble.
[11] When you are prosperous, they become your second self, and lord it over your servants;
[12] but if you are brought low, they turn against you, and hide themselves from you.
[13] Keep away from your enemies, and be on guard with your friends.
[14] Faithful friends are a sturdy shelter: whoever finds one has found a treasure.
[15] Faithful friends are beyond price; no amount can balance their worth.
[16] Faithful friends are life-saving medicine; and those who fear the Lord will find them.
[17] Those who fear the Lord direct their friendship aright, for as they are, so are their neighbors also.
This passage contains many descriptions of true friendship vs. false friendship. Most people, in their relationships with others, have encountered most if not all of the examples of false friendship, and know first-hand how much it hurts to think someone is a true friend and have them turn against you.
The sad truth is that no human being is capable of being a friend in the way that the Lord can be to you. No person can love you as much as the Lord does. There is no such thing as a perfect friend. All friends will have flaws and each will have a set of problems (bad habits, sins, and so on). It is very important to realize that having good friends can be very helpful, but it is best to rely on the Lord and not make friendships with people have more importance than they should. A good relationship with the Lord should be one's primary goal in life, as verse 16 suggests. A healthy relationship with the Lord will cause you to be a better friend to other people (verse 17) and will cause you to find faithful friends (verse 16).
Is is very easy to get comfortable with a group of people that are considered to be friends and neglect the spiritual relationship with God. In doing so, trust gets placed in the people, and eventually, something will go wrong. Some people will turn out to be untrustworthy and others will be friendly as long as you are in good financial condition and good health, and don't otherwise seem to be having any problems. If a problem develops between you and a some friends, they may turn on you and try to turn others away from you as well. It is difficult to predict when such friends may turn on you, and I'm sure that everyone who reads this page will have plenty of examples from their own personal life as examples.
As a Christian, it is important to be a good friend to others. The "pleasant speech" and "gracious tongue" from verse 5 is important. Being pleasant is a key to making a positive impression, and it is crucial that the pleasantness is not artificial or for the wrong reason. Ask yourself, "Am I being nice to this person because I want them to like me so I may somehow benefit from them liking me, or do I want to be a true friend to them regardless of whether they like me back and regardless if I ever get anything in return?" Ask yourself, "Do I really care about this person? As a Christian, do I love this person and wish for their salvation even if they turn out to have detrimental flaws or turn out to be a terrible enemy?" If you cannot answer yes to both of those questions, then your relationship with God and your understanding of His Word needs improvement. A "no" answer puts you in danger of becoming a friend that will fall away when someone needs you or becoming an enemy.
Being a good friend is not easy. It takes work and discipline. There will always be temptation to betray a friend for your own benefit or shy away from a friend in time of trouble and those temptations must be resisted. After having a quarrel with a friend, in a time of anger, it is tempting to tell others, in anger, about the problems. Doing so just does more damage, and makes it more difficult to remain friends after the anger passes.
The most important point in this entire study is that the key to healthy friendships with people is a healthy relationship with the Lord.
Translation abbreviations used: