It’s good for saints to pray for each other (Ja 5:16a), and effectual, fervent prayers of righteous souls can make a real difference. (16b) Paul asks his brothers to pray for himself and for those working alongside him (He 13:8), at times even begging in the strongest possible language. (Ro 15:30) So, is it reasonable to ask saints in Heaven to pray for us?
Though all saints are part of Christ’s body, the Church (Ep 5:25-27), including those in Heaven (He 12:23), there are significant difficulties with this practice.
Firstly, it presumes the souls to whom we’re praying actually are in Heaven, that they’re true believers. However, unless scripture explicitly affirms this it’s presumption. There’s nothing stopping God from working through an unregenerate soul (Samson? King Saul? Jonah? Nebuchadnezzar?) to accomplish His purposes. We can therefore safely claim salvation for only very few, such as Abraham (Lk 16:23), the Twelve (except Judas: (Jn 17:12)), Paul (2Ti 4:7-8), etc. For example, scripture doesn’t explicitly tell us that Mary, Christ’s mother, ever came to true faith; she evidently lived many years after His birth without it. (Mt 12:47-50) She’s likely in Heaven, but there’s no way to be sure until we get there.
Secondly, praying to Heavenly saints presumes they can hear us across the immense expanse of the universe, which is, again, presumption; there is zero indication of this in Scripture.
Further, if it’s right to pray to saints at all, it’s right for a billion souls to pray regularly to a given saint (e.g. Mary), yet this is essentially attributing infinite capability to a finite soul, elevating them to godlike status. Distinguishing this from an affirmation of omnipresence and omniscience is semantics at best; the practice is therefore evidently unreasonable and problematic.
So, given such uncertainties, why would we spend any time at all asking saints in Heaven to pray for us? (Co 4:5) If it could be a waste of time (and it certainly could be), can it be excellent? (Php 1:10a) If we can’t prove it’s the will of God (Ro 12:2), why would anyone recommend it? On what authority?
If it’s good and right to ask saints in Heaven to intercede for us, and we’re unable to verify this from Scripture alone, Scripture must be incomplete as a lamp to our feet, and a light to our path. (Ps 119:105) We then require other (and necessarily fallibly human) sources of light. Yet this violates 2Ti 3:16-17; a fundamental claim that Scripture alone is sufficient to perfect us, to equip us to all good works. It’s one thing for teachers to show us how to rightly interpret Scripture, it’s another thing altogether to require secret, extra-biblical revelation or knowledge to live a godly life: this is Gnosticism.
Finally, since Christ Himself (He 7:25) and the Holy Spirit (Ro 8:26) are always praying for us, why would we need others in Heaven to intercede for us as well? They certainly aren’t any closer to God than God Himself.
God knows what we need before we ask (Mt 6:8); our prayers don’t inform God. Evidently, the purpose of prayer is primarily to engage us in pursuing and experiencing God’s will, which makes sense for believers on Earth. When we ask according to His will, we know He hears and answers us. (1Jn 5:14-15)
In presuming Christ came to start a new religion, which appears to be inherent in such ideas, we invariably find ourselves in error. He didn’t. (Mt 5:19) Ultimately, if what we’re saying and doing isn’t grounded in Torah itself, it’s darkness. (Is 8:20)