He that doubteth (ο διακρινομενος). Present middle participle of διακρινω, to judge between (δια), to hesitate. See James 1:6 for this same picture of the double-minded man. Cf. Romans 4:20; Mark 11:23.

Is condemned (κατακεκριτα). Perfect passive indicative of κατακρινω (note κατα-), "stands condemned."

If he eat (εαν φαγη). Third class condition, εαν and second aorist active subjunctive. If in spite of his doubt, he eat.

Whatsoever is not of faith is sin (παν ο ουκ εκ πιστεως αμαρτια εστιν).

Faith (πιστις) here is subjective, one's strong conviction in the light of his relation to Christ and his enlightened conscience. To go against this combination is sin beyond a doubt. Some MSS (A L etc.). put the doxology here which most place in Romans 16:25-27. But they all give chapters 15 and 16. Some have supposed that the Epistle originally ended here, but that is pure speculation. Some even suggest two editions of the Epistle. But chapter 15 goes right on with the topic discussed in chapter 14.

Romans 15:1

We the strong (ημεις ο δυνατο). Paul identifies himself with this wing in the controversy. He means the morally strong as in 2. Corinthians 12:10; 2. Corinthians 13:9, not the mighty as in 1. Corinthians 1:26.

The infirmities (τα ασθενηματα). "The weaknesses" (cf. ασθενων in Romans 14:1; Romans 14:2), the scruples "of the not strong" (των αδυνατων). See Acts 14:8 where it is used of the man weak in his feet (impotent).

To bear (βασταζειν). As in Galatians 6:2, common in the figurative sense.

Not to please ourselves (μη εαυτοις αρεσκειν). Precisely Paul's picture of his own conduct in 1. Corinthians 10:33.