6. Give biblical justification for your view upon whether or not physical abuse should be considered legitimate grounds for divorce.
I will consider the case of the husband inflicting physical abuse on his wife in the light of the following New Testament Scriptures about marriage :
1 Corinthians 7:3-5
1 Corinthians 7:10-16
First, what is marriage ?
Marriage is the uniting of two people to make up "one flesh" (Matt 19:4-5) accompanied with Jesus' injunction that "what God has joined together, let man not separate" (Matt 19:6). This is the ideal.
But Jesus recognises we no longer live in an ideal world (Matt 19:8). And so divorce is permitted but NOT for "any and every reason"(Matt 19:3)
The reason why the teaching on divorce is of such great concern is not merely for the divorce itself (as bad as that is since it goes against Jesus' injunction) but also because re-marriage subsequent to a divorce obtained for an invalid reason brings with it the sin of adultery (Matt 19:9).
And so Jesus limits allowable re-marriage to a divorce for "marital unfaithfulness" - only.
Having set the framework for marriage, divorce and re-marriage I will now turn my attention to the case of whether or not physical abuse should be considered legitimate grounds for divorce.
Whether the abusing husband is a believer or not has, in my opinion, little bearing in this particular situation. In either case a temporary or permament separation (not divorce) might be advisable for pastoral reasons and for reasons of safety for the abused.
This arrangement, of course, may be refused by the abusing partner on the grounds of conjugal rights. The abused wife may find ground in a continued refusal to be with her husband in view of how the marriage between a man and a woman is to mirror the relationship between Christ and his church (Ephesians 5) and as it can be inferred from this passage abuse has no place in the marriage relationship.
Of course, the abused wife should not be the first to seek divorce (1 Corinthians 7:10-16) . If her husband does so on the grounds of his wife's failure to fulfill what he might insist is her "marital duties" then he may divorce her and presumably seek re-marriage in which case the abused wife would be free to re-marry herself since her husband would effectively have committed "marital unfaithfulness" by his own remarriage.
The fact that a parent abuses a child does not nullify the reality of a parent-child relationship as dysfunctional and sinful as that may be. Similarly, I cannot agree that physical abuse (as bad as that is) is legitimate ground for divorce. Physical abuse may, however, trigger a train of events terminating in divorce but not as a legitimate ground in itself for Jesus already settled the matter of legitimate ground by limiting it to "marital unfaithfulness".