Romans 14:3 needs to be understood in light of Romans 14:1. The command of Romans 14:3, namely not to despise a fellow Christian who abstains [from meat], and let not the one who abstains pass judgment on the one who eats, for God has welcomed him
(Romans 14:3). Strikingly, Paul here in Romans 14:3 employs the same verb as in Romans 14:1 when stating that God has welcomed him.
This welcome (or acceptance) by God constitutes more than a mere formal recognition, rather conveying the idea that God himself has taken this brother or sister into his service, and that the Lord has taken the care of these servants upon himself. This serves as a blueprint for the mutual interaction between Christians, in order to prevent them from condemning each other: 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
(Romans 14:4). Whether you are strong or weak in faith does not determine the future. Ultimately it is the Lord who carries his children and leads them to what he called them to be.1
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.