“holiness, without which no man shall see the Lord” [Hebrews 12:14]

“holiness, without which no man shall see the Lord”. We have two things here – holiness and seeing the Lord.
Holiness is a state of purity, being set apart for God’s glory. For man as he tries to draw near to God it is a progressive state. To be like Jesus is the path along which we advance.
Refusing to acknowledge sin, or to say sin does not exist, does not make me holy. Only absolution and forgiveness can do that and then it must be through the blood of Jesus.
Seeing the Lord can just mean recognising He is the Lord God Almighty. As the life of holiness proceeds the follower sees more and more of Jesus.
The important thing is that you cannot see the Lord until you are made holy and you can only begin to be holy when sin is recognised, renounced and forgiven.