All Men Are Sinners
After Adam sinned, the human race was corrupted, and everyone born was born separate from God. (Genesis 2:15-17, 3:1-24, 8:21, Romans 5:12, 3:10-18, James 2:10-11) Even a man's "righteous" deeds, prayers, sacrifices, etc. are offensive to God in that state! (Isaiah 64:6, Isaiah 59:1-2, Proverbs 28:9, 15:8) NOTE: Christians generally believe that this is why Jesus had to be born of a virgin - the sinless sacrifice of Jesus was essential to God's plan. (Luke 1:26-35, Hebrews 4:15, 1 Peter 2:21-23)
"for all have sinned and fall short of the glory of God" (Romans 3:23, NASB)
This is a major problem which earns us eternity in Hell. (2 Thessalonians 1:8-9, Revelation 20:11-15, 21:1,10,27)
God's Redemptive Plan
God had a plan for redemption though, and immediately began reaching out to mankind, foreshadowing the coming of Jesus, and encouraging people to return to Him and trust Him for their salvation. (Genesis 3:21, Hebrews 10:1-10, Romans 7:7, Galatians 3:24, Colossians 2:16-17) In God's love, He sent His only Son to come and pay the penalty for our sin - death. (John 3:16, Romans 5:8, 2 Corinthians 5:21) In fact, not only was justice served, but those who belong to Christ actually have their sins removed. (1 John 1:7, 3:5, Psalm 103:12, Isaiah 43:25, Hebrews 10:14) This fixes the "problem". (Romans 6:23, 8:1)
"Life in Christ"...?
There are essentially three things which define the life of someone who is "in Christ":
Living in submission to His Lordship (Matthew 7:21, Romans 6:22)
Walking in His love (John 13:35, 1 John 4:7-8, Luke 10:25-28)
Being led by His Spirit (Romans 8:9, 13-14)
(With some understanding it becomes clear they are all the same thing.)
"and He died for all, so that they who live might no longer live for themselves, but for Him who died and rose again on their behalf." (2 Corinthians 5:15, NASB)
It is important to note, though, that God's will is often different than what we think is good. (Isaiah 55:8) If God has called you to work in a factory, but you lock yourself away in an Abbey somewhere, you are in disobedience. (1 Thessalonians 4:11, Hebrews 5:4, 1 Corinthians 7:17) If God calls you to rebuke someone, but you shrink back, you are in disobedience. (2 Samuel 12:1-15, Hebrews 10:38)
Crossing Over
A life "in Christ" is the opposite of a life "outside of Christ". (1 Peter 4:1-5) So to "repent", or "convert" is to die to your old life and live for Him. (Acts 17:30, Romans 6:6, Galatians 2:20) This death involves turning everything over to Him. (Luke 14:27-33, Galatians 5:17,24) This is a drastic decision that can only truly be made out of sincere sorrow for our old life of offense to God. (2 Corinthians 7:10)
"For you were continually straying like sheep, but now you have returned to the Shepherd and Guardian of your souls. " (1 Peter 2:25, NASB)
Judge Yourself
It is good for us to consider carefully whether we are "in Christ". (2 Corinthians 13:5) Have I surrendered my life to the Lord? (Luke 17:33) Do I desire to do His will above my own? (Matthew 6:10, 26:42) Am I living ("dying") this way daily? (Luke 9:23, 1 Corinthians 15:31)
We all make mistakes, but God is patient and forgiving toward His people. (James 3:2, Nehemiah 9:17, James 5:16, 1 John 2:1) The question is - are we sincerely trying to follow Christ out of a serious repentance and love? (Hebrews 10:26) If we are, God will honor that. (Proverbs 24:12, Jonah)