The consequences as far as in this life may be far worse for some sins vs. others, but just one sin will keep us out of heaven if we aren't in Christ since God requires perfection to enter heaven, and there is only one way we can have that, and that's to be in Christ:
James 2:10
For whoever keeps the whole law but fails in one point has become accountable for all of it.
Matthew 5:48
You therefore must be perfect, as your heavenly Father is perfect.
Romans 10:
1Brothers, my heart’s desire and prayer to God for them is that they may be saved. 2For I bear them witness that they have a zeal for God, but not according to knowledge. 3For, being ignorant of the righteousness of God, and seeking to establish their own, they did not submit to God’s righteousness. 4For Christ is the end of the law for righteousness to everyone who believes.