I am in a deep debate regarding with my nephew. He has stumped me with two questions.
Question 1: I’ve argued that marriage and the marital act must always be open to life. However, since the marriage between an elderly woman and man is not, how can we hold the position that all marriages (and marital acts) must be open to life to be valid? Note, he brought this up as part of a response to my arguments against gay marriage (relative to unitive and procreative principles for marriage).
Question 2: If a couple has an licit reason for temporararily avoiding pregnancy (and corresponding intention to have children later), and the couple is in full agreement on this reason (in turn taking away from my argument that the marital acti than turns the woman and/or man into an object for sexual gratification), than why can they not use artificial birth control during that time? What is the difference to using NFP?
Also, related to this, he proposes that the sin of Onan was really about Onan not wanting to have relations with the widow of his brother, and not essentially about birth control - so that the Bible really does not forbid birthcontrol. I realize that the church fathers and constant church teaching have clearly been against artificial birthcontrol.
Thank you for any help (and relevant sources / quotes)