Some gay relationships are an example to others, said Justin Welby. Though the new archbishop's opposition to equal marriage has disappointed some pro-equality activists, these are the most positive remarks any archbishop has made about gay relationships while in office. By following this up with practical measures, he could strengthen the Church of England's credibility in sharing the good news of God's love for all.

Welby was formerly a conservative evangelical with rigid views, but his openness to learning and growth has led him to value other traditions and re-examine his stance on sexuality. When his appointment was announced, he declared that "we must have no truck with any form of homophobia", and pledged to "listen very attentively to the LGBT communities, and examine my own thinking prayerfully and carefully".

In his interview this week with Iain Dale on LBC radio, he went further. "I know plenty of gay couples whose relationships are an example to plenty of other people," he stated. He would not suggest that the love between gay partners "is less than the love there is between straight couples, that would be a completely absurd thing to say".

When asked if he would be open to discussion on government proposals for marriage equality, he replied: "We are always open to discussions." But the historic teaching of the church, "and this is where I remember that I've got 80 million people round the world who are Anglicans, not just the one million in this country – has been that marriage in the traditional sense is between a man and woman for life".

However, he added: "I think we need to find ways of affirming the value of the love that is in other relationships."

There is much he could do, despite the restrictions of the Church of England's official position on sexuality. This is under review and a report is due in late 2013, which may open the door to further progress.

The current stance, set out in 1991 by the house of bishops, recognises that Bible passages must be read in context, sexual orientation does not usually change and, among gay and lesbian as well as heterosexual couples, "there are those who grow steadily in fidelity and in mutual caring, understanding and support, whose partnerships are a blessing to the world", and who achieve "heroic sacrifice and devotion".

While celibacy is advised for those attracted to the same sex, it is recognised that some lay people may, in good conscience, take a different view: the church should be a welcoming place for them. Those who enter physically intimate partnerships should be encouraged to form faithful lifelong relationships. To avoid scandal and uphold church teaching, clergy should not have this freedom, according to the 1991 publication, Issues in Human Sexuality, but they should not face "intrusive interrogations".

More theologians now recognise that same-sex partnerships can be morally right, including the lead author of Issues, as do most Anglicans in Britain. Yet, while many congregations are welcoming, some are not, and church leaders' public statements alienate many LGBT people and their families and friends.

Welby could start by taking action to protect LGBT lay people in every parish, celibate or otherwise, from discrimination, and clergy from invasive questions. There are disturbing instances where people are made to feel unwelcome or humiliated and this should stop.

He could also encourage more thinking about how churches provide, and could improve, pastoral support for same-sex couples, including celebrating civil partnerships. In time, the Church of England might agree an order of service which clergy could use if they wished.

While all Anglican churches should indeed consult others in the communion before major decisions, this cuts both ways. The archbishops most opposed to greater inclusion have resisted repeated calls by international gatherings since 1978 for "deep and dispassionate" study of the issues, taking account of scientific research, and for dialogue with homosexual people and support for their human rights. Yet these leaders have not even bothered to explain why. Their treatment of their LGBT members falls far short of gospel values of love and justice.

Within the Church of England and beyond, Welby could promote awareness and discussion of developments in theological thinking on sexuality, including marriage. Overseas leaders could participate, but would have to engage seriously with others' arguments.

The current situation is harming LGBT people and Christian witness in England. It is time to start moving forward on inclusion.

• This article was amended on 15 March 2013. An error in editing led to the title of the 1991 pamphlet Issues in Human Sexuality being changed to Some Issues in Human Sexuality, which is a different publication. This has now been corrected.