Biologically: No. It is advantageous to both genders to breed with multiple mates. With each of ones offspring being the combination of yours and a different mate’s genes, a disease that infects any one of your children will have a different probability of infecting the others.

Assuming a non zero chance of mortality for any infection, then by combining your genes with those of a different mate for each of your children maximizes the probability of your genes being passed on to subsequent generations.

Culturally Yes. Societies in which inheritance rights are assigned a high social value have historically needed monogamous, non-incestuous, bloodlines to identify who is entitled to the property.

I think that you will find that the teachings of "the church" tend to follow local customs. For example "the church" to which I suspect you refer, arises from pre-modern Europe, from whence the laws of primogeniture also arise. In Africa and Asia, where the local customs were rather different, the indigenous churches accommodated the particulars of those societies.

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Eudaimonia