I recently heard about the phrase "secret sin." But what actually is a secret sin? I searched all over and I could not find a clear answer. All I found talks about that consequences of it, but there's no explanation of what it is. Please explain it to me.
You are looking for a particular type of sin, but all "secret sin" refers to are those sins an individual does that he thinks no one else knows. "You have placed our iniquities before You, our secret sins in the light of Your presence" (Psalms 90:8). Of course, no sin is truly secret because at a minimum God is aware of all that we do. "For there is nothing covered that will not be revealed, nor hidden that will not be known" (Luke 12:2). "Therefore judge nothing before the time, until the Lord comes, who will both bring to light the hidden things of darkness and reveal the counsels of the hearts. Then each one's praise will come from God" (I Corinthians 4:5).
Some sins are secret because we refuse to acknowledge them. We hide them from everyone, including ourselves. "Who can discern his errors? Acquit me of hidden faults" (Psalms 19:12).
The most common "secret sin" is usually the viewing of pornography, but it isn't limited to that. In the days of Ezekiel it was idolatry. "Then He said to me, "Son of man, have you seen what the elders of the house of Israel do in the dark, every man in the room of his idols? For they say, 'The LORD does not see us, the LORD has forsaken the land'" (Ezekiel 8:12). For some people it is drinking or drug use. Basically any sin a person keeps hidden from other people is a secret sin.