First, there is repentance from being a child of Satan, and becoming a newborn child of God > Ephesians 1:12, Acts 26:18.
Can one fully repent 100% and maintain it in this world...?
Then there is correction . . . for every child of God > Hebrews 12:4-11. I see this scripture means that every child of God will always need more correction, somehow. So, yes we keep changing . . . metanoia . . . as far as needing more to become like Jesus who can not sin.
Can one fully repent 100% and maintain it in this world...? (be a sinless one) (and what does that look like...?)
I personally now understand that God is conforming all of us to become like Jesus, but we still have stuff not perfectly like Jesus in our nature; so more or less wrong stuff still can get the better of us. But as Jesus grows in us as our new inner Person > Galatians 4:19 < He takes the place of the human nature which is capable of sinning in various ways.
More and more, we are "strong in the Lord and in the power of His might" > please see Ephesians 6:10. And do consider how Jesus in us is almighty against however we could sin. More and more, we share with Jesus in us. And so we become more loving and pleasing to God even like Jesus His Son is so pleasing (2 Corinthians 3:14-15, Ephesians 5:2). And Jesus has us learning >
"'Take My yoke upon you and learn from Me, for I am gentle and lowly in heart, and you will find rest for your souls.'" (Matthew 11:29)
So, our attention needs to be to Jesus, most of all . . . not to if and how much we are sinning. God can keep score on that, as much as He pleases; but God is busy with bringing real correction and Jesus is busy with having us learn all Jesus has us learning.
So, a good question might need to be . . . what is Jesus having us learn? What do we learn simply by having Jesus growing in us as our new inner Person?
We learn how God's love has us becoming like Jesus, how we become pleasing to our Father the way Jesus in us has us becoming pleasing to our Father. We also discover how we become able to relate with one another while also even loving and having hope for any and all people.
This is what grace does in us; we learn how grace works, by actual experience of how God in His love in us cures our nature and has us sharing with Him and loving . . . more and more like Jesus.
Jesus in us has us discovering this . . . demonstrating > a teacher does not only tell us things, but demonstrates and gives us laboratory experiences.
What do we need to repent of...?
"all have sinned and fall short of the glory of God" (in Romans 3:23). God desires to share with us in His very own glory > John 17:22-26. So, we sin by not sharing with our Heavenly Father and Jesus and the Holy Spirit in Their very own glory. Therefore, we are predestined by God "to be conformed to the image of His Son, that He might be the firstborn among many brethren." (Romans 8:29)
Plus, we need to love, more and more the way Jesus loves us as His family and dearly and compassionately and with hope loves even God's enemies. Jesus on the cross died with hope for any evil person, at all > love "hopes all things" (in 1 Corinthians 13:7).
So, God is changing us to be more and more mature in His love, so we share-so with Him and our Groom Jesus and one another >
"Love has been perfected among us in this: that we may have boldness in the day of judgment; because as He is, so are we in this world." (1 John 4:17)
Does your definition of repent fit my definition of repent, cause repentance can mean just a change of mind...? How can a man judge that...?
I think your mind is deeper than just what you are thinking. There is the spiritual nature of our mind, which makes us natural at what we do. Our mind can mean our disposition . . . effecting what we mind with our attention, what we mind doing and having happen to us. So, our mind and heart are possibly related to each other. Surely, Jesus does not want only our minds to change, meaning only our thinking.
"and be renewed in the spirit of your mind," (Ephesians 4:23)
So, we need how God changes us where our thoughts and feelings and reactions and choices are coming from >
"for it is God who works in you both to will and to do for His good pleasure." (Philippians 2:13)
Are there steps and stages to repentance?, or do people differ from one another, each with it's own unique and different abilities/inabilities, and different strengths and weaknesses...? Are people equal...?
Each of us is a member of the body of Jesus. Members have similarities, but also major differences. We all need the same love blood of the Holy Spirit. We all need energy of love. We all need nervous and endocrine regulation.
But things we do can be very different, but while each of us receives and ministers-on the grace of how God's love effects us and matures us "in all things" > please see Ephesians 4:15 in context, and >
We all help one another, ministering God's own grace to one another > 1 Peter 4:9-10. And no part of a body grows stronger and healthier all by itself. We grow together, and mature together.
I would like some power over certain kinds of sins right now,
"Confess your trespasses to one another, and pray for one another, that you may be healed. The effective, fervent prayer of a righteous man avails much." (James 5:16)
"Do all things without complaining and disputing, that you may become blameless and harmless, children of God without fault in the midst of a crooked and perverse generation," (in Philippians 2:14-16)
This is possible with God, and God does no less in us. So, we fail because we choose the wrong things or because we are trying to make ourselves change. We need to look to and purely depend on God, submit to Him, discover how He succeeds.
And notice how Paul says to stop "complaining and disputing" > these are anti-love things. As we get strong in love, we become more and more easily able to stop what is directly against loving God and loving people. And the foolish and selfish pleasure stuff will become less and less as we become so satisfied in God's love and His stability . . . shared with us . . . while we share with Him in His glory of this love.