Justin Welby is walking a fine line.

As Archbishop of Canterbury he has overseen a number of cross-faith initiatives between Christians, Muslims, Jews and other faiths. Yet he has also begun the biggest evangelism project in the UK for decades.

As such he's avoiding twin traps. One is that of religious relativism where all faiths are seen as the same. The other is religious fundamentalism where Britain is seen as a Christian country where all other faiths are a dangerous threat. Both Welby's immediate predecessors flirted with these traps.

Although widely misunderstood, Rowan Williams' comments on the sharia law meant his inter faith efforts seemed woolly at best. There was a danger that in Williams' era, inter faith discussion meant a select group of people gathering to discuss inter faith issues and pat each other on the back for how accepting they were.

George Carey risked falling into opposite extreme of alienating communities he could have reached out to. He has criticised Islamic leaders for not speaking out strongly enough against terrorism and said Islam was associated with violence across the world. More recently he has said too many Muslims have come to Europe and said multiculturalism has led to pockets of sharia law operating in the UK.

No one can doubt Justin Welby's focus on evangelism. With the Archbishop of York he wrote to every single church in the UK to urge them to pray for "all to respond to the call of Jesus Christ to follow him" in the build up to Pentecost.

Clearly he is not afraid to assert the differences between Christianity and other faiths in the UK. "We have different narratives and we disagree about some of the central features in our narratives," he told an inter faith gathering on Thursday at Lambeth Palace.

Yet there is an openness and willingness to emphasis the common ground and work together. "We believe in the idea that life only makes sense in the context of an overarching narrative based in our scriptures, our traditions, in our community lives and in our history," he continued to the Near Neighbours gathering on Thursday. On top of this, his statements in response to terror attacks such as in Paris never condemn Islamic communities and always emphasise unity. 

In maintaining the balance between asserting the primacy of his faith while working with other religious groups, Welby has understood that the best way to evangelise is from within. Carey spoke of a "decade of evangelism" but it was a relative failure. Williams risked the impression he was too concerned with inter faith relations to focus on evangelism. Welby on the other hand is in a much better place. He speaks of evangelism from a position of positive relationships with other faith leaders. He can evangelise around the table rather than shouting from street corners.

Welby is walking the line and we should pray that we all benefit from the results.