You can rationalize anything, even the zany ideas listed below:

Every way of a man is right in his own eyes: but the LORD weighs the hearts. Proverbs 21:2

Whatever is not of faith is sin.  Romans 14:23

• Adultery
• Perversion of marriage
• Fornication
• All types of perversion
• Killing an unborn baby--Abortion
• Blowing up an abortion clinic
• Taking drugs, marijuana, etc.
• Disrespect to parents
• Political correctness
• Lawlessness
• Differences in beliefs between Christian groups
• Rudeness
• Anger
• Lack of forgiveness
• Malice
• Men who don't love their wives
• Women who don't respect their husbands
• Divorce
• Beating up a spouse
• Killing a spouse
• A nation that doesn't defend its citizens against killers
• Unfounded accusations
• Dedication to political systems for security
• Failure to vote
• Dividing the church over temporary systems
• Failure to discern the Body of Christ
• Man-made religious forms and rituals
• Man-made church governments
• Claims that Darwinism is science
• The government taking over the role of church
• Judicial activism
• Euthanasia
• Wild Governmental spending
• Faulty logic age-of-the-earth calculations
• Global warming phobia
• Hole-in-the-ozone-layer phobia
• Ecological ideas that go beyond the facts
• The notion that free speech is good except for Christians and conservatives
• Relativism
• Communism/Socialism
• Belief in rationalized supposition
• Looking to the intellect (rationalized supposition) instead of God 
• Biblical error claims
• Manipulation of the election process
• Extreme zeal for politics--politics as religion
• Naturalism
• Humanism
• Atheism
• Materialism
• Naturalistic or materialistic interpretation of Scripture
• Adding to or taking from Scripture

... and this is just a partial list.  The human mind is capable of generating more nonsense than could possibly be recorded or anticipated.

How far out on the rationalistic limb people will go depends on the degree to which they want something to be true.