Rom 14:21 [It is] good neither to eat flesh, nor to drink wine, nor [any thing] whereby thy brother stumbleth, or is offended, or is made weak.
Rom 14:22 Hast thou faith? have [it] to thyself before God. Happy [is] he that condemneth not himself in that thing which he alloweth.
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First note that the issue of drinking wine is brought up. Again, here we note it is not some new idea conjured up in the early to mid 1900's. It was an issue back in the times of the apostles.
Also note that Paul does not in any manner state do it privately or just not when they are around. He states that if you have faith, then keep it between you and God so as not to cause your brother to stumble. Chapter 15 expounds our responsibility to our brothers/sisters in Christ - bearing their weeknesses and pleasing to them for their edification. (15:1-2), then it goes on to tell us that Christ did not do as He pleased (to please Himself) but, verse 5, that we are to be like minded as Christ to put our brothers faith and spiritual growth before our own legal rights. And he continues on in that chapter..
In 1 Cor 8 Paul takes this thought to a personal level for himself (as uses himself as the example frequently) in which:
1Cr 8:9 But take heed lest by any means this liberty of yours become a stumblingblock to them that are weak.
1Cr 8:10 For if any man see thee which hast knowledge sit at meat in the idol's temple, shall not the conscience of him which is weak be emboldened to eat those things which are offered to idols;
1Cr 8:11 And through thy knowledge shall the weak brother perish, for whom Christ died?
1Cr 8:12 But when ye sin so against the brethren, and wound their weak conscience, ye sin against Christ.
1Cr 8:13 Wherefore, if meat make my brother to offend, I will eat no flesh while the world standeth, lest I make my brother to offend.
In the above we note that for the person who continues doing what they KNOW another person believes is sin. The person 'doing it', even though they they can legally do it, are sinning not only against their brother but also against Christ Himself.
Lastly also note how he leaves the matter as to when you 'can' do it (using himself as the example -noted in such places as 1 Cor 11:1 and others-), in verse 13. He does not state he will do it privately, or when they are not around, but that he will never partake if a brother considers something sin. He does this for THEIR sakes. Our liberty is not to do what we like because we can.. it is to NOT do even though we can.
Based on the above, it is reasonable to postulate that Paul did not drink socially or for pleasure but if he partook at all.. it would ONLY be for the health benefit to his body in the smallest amount so that he could continue to preach and teach the Word of God. And is why he encourages Timothy to no longer drink ONLY water but to take a 'little' wine (mixed with water) to help aid his common malady.