In Lamentations the word goy or ‘nations’ is used. There is no separate reference to ‘pagan’ which suggests that the translators wanted to differentiate it from Isaiah 56:6-7. The ‘nations’ entering the sanctuary was forbidden. During the days of Antiochus Epiphanes, the goyim, the Greeks, entered the sanctuary and defiled it with pig’s blood. Their actions were pagan and they were goyim.
Abraham did not become the ‘father of many pagans’ nor should every gentile be considered pagan. Abraham became the ‘father’ of many geographical peoples with many different origins, languages, and governmental identities: the goyim [nations]. Though those living in the nations may have had a pagan belief system, many within those systems recognize Abraham as their ‘father of faith.’ These are the goyim promised to ‘the father of many nations.’
Unfortunately, the world has contaminated the minds and hearts of many believers accordingly. Rather than being transformed by the renewing of their minds, they play with the fruitless deeds of darkness rather than expose it for what it is. We should be praising God for calling us out of darkness into His glorious light not paying tribute to the darkness (1 Peter 2:9, 2 Corinthians 6:17-7:1).