That's the difficulty I've been having--balancing the two doctrines.
The issue is I can't get around verses like Ro 14:5, 23, but I think they don't conflict with Ro 5:1 if you don't see yourself getting right with Jesus, and obtaining peace, by walking in love and faith, but that what is not present and what becomes effected and present is falling away from that by sin, but that you're only remaining with Him and the peace you're already in (Ro 5:1) by doing your walking in love and grace and faith, bc sin (not walking in love and faith) disturbs the peace you have by faith, but the peace should already be there by the Foundation Christ.
Let's look at the passages you mention.
Rom 5:1 Therefore, since we have been justified by faith, we have peace with God through our Lord Jesus Christ.
Rom 14:5 One person esteems one day as better than another, while another esteems all days alike. Each one should be fully convinced in his own mind.
Rom 14:23 But whoever has doubts is condemned if he eats, because the eating is not from faith. For whatever does not proceed from faith is sin.
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But the whole chapter and theme of Rom 14 is not to pass judgements on each other.
Rom 14:3 Let not the one who eats despise the one who abstains, and let not the one who abstains pass judgment on the one who eats, for God has welcomed him.
Rom 14:4 Who are you to pass judgment on the servant of another? It is before his own master that he stands or falls. And he will be upheld, for the Lord is able to make him stand.
Rom 14:10 Why do you pass judgment on your brother? Or you, why do you despise your brother? For we will all stand before the judgment seat of God;
Rom 14:13 Therefore let us not pass judgment on one another any longer, but rather decide never to put a stumbling block or hindrance in the way of a brother.
Rom 14:22 The faith that you have, keep between yourself and God. Blessed is the one who has no reason to pass judgment on himself for what he approves.
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Romans 14 reminds me of Jesus words in Matt 13:8
Matt 13:8 Other seeds fell
on good soil and produced grain,
some a hundredfold,
some sixty,
some thirty.
The Lord is full of mercy, He knows our weaknesses and does not expect everybody to produce
hundredfold.
In mercy is no contradiction.
Hope this helps.