The letter to the Hebrews has this to say about seeing God.
Seek peace with all people, and the holiness without which no one can ever see the Lord. (12:14, NJB)
Without holiness no one can ever see God. This contradicts the Protestant view of sola fide, according to which one is justified by faith alone (and thereby goes to heaven). Of course, the previous chapter of Hebrews is famously devoted to the value and necessity of faith, and I do not mean to deny that, but there is a holiness which Christians (the addressees of the letter) must seek and without which they will not see God. The Protestant’s sola fide is insufficient; we must also live holy lives. Bear in mind: he is addressing Christians. Hence on the Protestant view there is nothing left to be done…and yet Hebrews says otherwise.