What makes someone an “insider” or an “outsider” according to Buddha Dharma and Sangha

Tipitaka is teaching about "How to receive the whole 6 profits": this life profit, next life, nibbāna profit, own profit, the others profit, and social public profit (atthattha, parattha, attāparattha, diṭṭhadhammattha, samparāyikattha, and paramattha).
Target of every teaching in tipitaka is just nibbāna profit, if not, it is not buddha's teaching, outsider. It is just the other religious teaching, although that religious member can attains wholesome jhāna (añña-titthiya/diṭṭhi in V.N. Mahavagga Mahākhandhaka).
There may have many teaching that available in the other religious, too. However, just buddha can be the first teacher who can teach that how to get the whole 6 profits, because only buddha can enlighten anatta by himself and teach to the other.

9. "Bhikkhus, there are these four kinds of clinging. What four? Clinging to sensual pleasures, clinging to views, clinging to rules and observances, and clinging to a doctrine of self.
10. "Though certain recluses and brahmans claim to propound the full understanding of all kinds of clinging, they do not completely describe the full understanding of all kinds of clinging.[7] They describe the full understanding of clinging to sensual pleasures without describing the full understanding of clinging to views, clinging to rules and observances, and clinging to a doctrine of self. Why is that? Those good recluses and brahmans do not understand these three instances of clinging as they actually are. Therefore, though they claim to propound the full understanding of all kinds of clinging, they describe only the full understanding of clinging to sensual pleasures without describing the full understanding of clinging to views, clinging to rules and observances, and clinging to a doctrine of self.
11. "Though certain recluses and brahmans claim to propound the full understanding of all kinds of clinging... they describe the full understanding of clinging to sensual pleasures and clinging to views without describing the full understanding of clinging to rules and observances and clinging to a doctrine of self. Why is that? They do not understand two instances... therefore they describe only the full understanding of clinging to sensual pleasures and clinging to views without describing the full understanding of clinging to rules and observances and clinging to a doctrine of self.
12. "Though certain recluses and brahmans claim to propound the full understanding of all kinds of clinging... they describe the full understanding of clinging to sensual pleasures, clinging to views, and clinging to rules and observances without describing the full understanding of clinging to a doctrine of self. They do not understand one instance... therefore they describe only the full understanding of clinging to sensual pleasures, clinging to views, and clinging to rules and observances without describing the full understanding of clinging to a doctrine of self.[8]
13. "Bhikkhus, in such a Dhamma and Discipline as that it is plain that confidence in the Teacher is not rightly directed, that confidence in the Dhamma is not rightly directed, that fulfillment of the precepts is not rightly directed, and that the affection among companions in the Dhamma is not rightly directed. Why is that? Because that is how it is when the Dhamma and Discipline is [67] badly proclaimed and badly expounded, unemancipating, unconducive to peace, expounded by one who is not fully enlightened.
14. "Bhikkhus, when a Tathagata, accomplished and fully enlightened, claims to propound the full understanding of all kinds of clinging, he completely describes the full understanding of all kinds of clinging: he describes the full understanding of clinging to sensual pleasures, clinging to views, clinging to rules and observances, and clinging to a doctrine of self.[9]