Ps 134:2 says, “Lift up your hands in the sanctuary.”
1 Tim 2:8 “I desire therefore that the men pray everywhere, lifting up holy hands”
Why do we raise our hands in worship again? First let’s talk liturgical housekeeping, and then confession of sin.
Most of our songs are prayers to God, and so we have chosen to lift our hands at a couple points of the worship service in particular, usually sung responses to the Word or at the end of the service. The point is to pick a time in the service to deliberately do this all together, like we kneel at confession. Ps 95 says to kneel before the Lord in worship. It doesn’t say exactly when – we’ve chosen confession time to kneel. We’ve chosen sung responses as a time to deliberately, all together raise our hands. We don’t confine hand-raising or kneeling to these times. Some people lift their hands when a hymn is moving them. That’s great. We shouldn’t be bothered during worship when people do something Scripture directly says, like kneeling during some other part of the worship service, or lifting their hands when we pray.
As for confession of sin, We ought to be able to hold up holy hands that didn’t hit our sister last week, that refrained from sexual temptation last night. Did we use our hands to work hard all week, or did our hands play 20 hours of x-box? Lifting hands to God is a great opportunity to connect life to worship, and to reinforce that there ought to be no incongruity in this. Of course, if we are going to lift holy hands, then before the confession we can say: "we will lift holy hands in a few minutes. What were those hands doing this week? Let's confess our sins so that we can truly lift holy hands.