Self-interest is an important value to acknowledge and affirm. Self-interest protects boundaries of personal values and concerns. If self-interest is not acknowledged, then there is a more likely occasion of "sin". Sin being defined by missing the mark of affirming both self and other.
Self interest has been given a bad "rap" in many religious groups, as self-interest is in opposition to God's purposes or plan. God's purposes and plans are understood in various ways. But, God's purposes and plans are usually understood as something superior to what the individual might want to pursue. Selfishness is the height of sin in this sense, because "God comes first". But,self-interest is not necessarily selfish. Selfish is a label given to those who may not choose to have the same value or ultimate goals. There is room in free societies to "walk away" if another's goals don't fall in line with yours. This is not selfish, but self awareness. And self-awareness is the first step toward becoming concerned with one's own personal goals, what one wants to do with their life.
Self-interest protects one's life, liberty and the pursuit of happiness. This is an American's right by birth. And Americans use their liberty to choose their course and determine their life. American's are self-interested, in this way. Is there anything "wrong" with this?
Religion would say that one must deny oneself and take up their cross, meaning that self-interest would be in opposition to what "God wills". And that "will" is defined depending on the Christian group one is associated with. The social gospelers would think your life should be about the business of bringing in "God's Kingdom" through social justice. Their view is social and economic equality and political liberty. But, how is this different from the "secular human rights movement" or other forms of liberal organizations that are interested in bringing in Utopian dreams?
The conservative/evangelical would believe that self-interest would be in opposition to what they regard as most important, salvation. Salvation has many meanings depending on what denomination one asks. Some believe that being "born again" is an all important goal, while other believe that one must prove their faith through their life choices of "Kingdom building", etc.
I really believe that all of these people can be and are duped if they do not acknowledge and accept that one must be self-interested, if they do not want others to determine their course of action. Self-interest acknowledges one's values, personal goals, and personal life, which must be considered whenever one commits to anything. And negotiation of these aspects of personal concerns must be brought to the table early on, otherwise, one will be labelled as un-cooperative, rebellious, etc. We, in the West, would think it would be abhorrent for a man to pay the bride's family and take her away to become his wife, without any concern about the woman's personal choice. But, some religions/cultures think this is "right".
Some cultures believe that one doesn't have a right to freedom of speech if it subverts the government. But, these cultures are not free societies. This is what has happened over the years for political dissidents. Our Constitution guarantees that Americans have the right to free speech. But, recently, free speech has come under fire, because of religious or personal offenses. And individuals need to be honest and self-aware about why they are speaking out. Why are they doing what they are doing. Be self-aware and have valid reasons why one chooses to cause political "upheaval" and another's personal pain.
Self-interest makes sure that one is free to choose and is not doing what they do for approval, or to "fit in", but are doing what they do because they choose to do what they choose to do.These people are the only ones that are "free to choose" in the first place. Those that have come to understand themselves and what they will or will not do and what is of ultimate concern are those that are free "to be" and then, are free "to do".
And it is only free societies that allow such human development and choice.