The Thesolonians verses are saying that God will punish those people -- there is no need for any people to do it. Some would argue that also means people explicltly should not do any punishing, as that is God's perrogotive.
The Ephasians verse needs more context. Look at verses surrounding it:
And do not get drunk with wine, for that is debauchery, but be filled with the Spirit, addressing one another in psalms and hymns and spiritual songs, singing and making melody to the Lord with your heart, giving thanks always and for everything to God the Father in the name of our Lord Jesus Christ, submitting to one another out of reverence for Christ.
Wives, submit to your own husbands, as to the Lord. For the husband is the head of the wife even as Christ is the head of the church, his body, and is himself its Savior. Now as the church submits to Christ, so also wives should submit in everything to their husbands.
Husbands, love your wives, as Christ loved the church and gave himself up for her, that he might sanctify her, having cleansed her by the washing of water with the word, so that he might present the church to himself in splendor, without spot or wrinkle or any such thing, that she might be holy and without blemish. In the same way husbands should love their wives as their own bodies.
Christians are encouraged to submit to one another, and husbands are encouraged to love their wives, and give up everything for them. True, this passage is describing different roles for men and women, but it is not so one sided as you presented.
The Leviticus verse is from the Old Testament, which is law oriented, and does have many harsh punsihments. But Christianity teaches that "the wages of sin is death" (Romans 6:23) and "all have sinned and fallen short of the glory of God" (Romans 3:23). Basically, we ALL deserve to die by the standards of the Bible. Singling out one sin isn't really relevant. Christianity teaches that Christ sacrificed himself in our place for forgiveness of sins.
There are difficult and confusing passages in the Bible, but when the Old Testament is combined with the New, it is clear that the overall message of Christianity is love and forgiveness.