Exegesis:

ho pisteusas kai baptistheis ‘he who believes and is baptized’: the single definite article governing both participles joins the two verbs together in describing the man who will be saved; the clause could be translated, ‘the baptized believer.’

pisteuō ‘believe’: here and in v. 17 the aorist participle is used absolutely, ‘the believer’ (in Mark, the present active participle is used absolutely twice, 9.23, 42 – never the aorist participle).

baptizō (cf. Mk. 1.5) ‘baptize.’

sōthēsetai (cf. Mk. 3.4) ‘shall be saved’: in the theological sense; in apposition to ‘shall be condemned,’ the reference is eschatological.

ho … apistēsas (cf. v. 11) ‘the one who does not believe’: the aorist participle is parallel to ‘the believer’ in the previous clause, and may be translated, ‘the unbeliever.’

katakrithēsetai ‘shall be condemned’: the verb katakrinō is not used in Mark (cf. 10.33) in the theological sense, as here. The reference is obviously eschatological: ‘he shall be condemned in the Day of Judgment.’

Translation:

Believes is often translatable only by a transitive verb, requiring an object. In this instance one may use ‘the gospel’ (or ‘the good news’) as object.

For baptize see 1.4, and for save see 10.26.

Condemned is more than ‘judged’ or ‘denounced.’ There should be some connotation of judgment for sin, e.g. ‘he who does not believe still has his sin,’ implying a continuing guilt (Tzotzil), ‘whom God will cause to find sin,’ in which only an active form can be used (Copainalá Zoque), and ‘arrive to get words because of sin’ (Tzeltal). In some instances condemnation is spoken of in quite idiomatic ways, e.g. ‘condemnation will eat in him’ (Conob).

Quoted with permission from Bratcher, Robert G. and Nida, Eugene A. A Handbook on the Gospel of Mark. (UBS Handbook Series). New York: UBS, 1961. For this and other handbooks for translators see here .