Absolutely. Christianity is testable using Lennox's procedure.

And it is congruent with the Scientific Method.

Popper's False Equivalence

First, let's address a false dichotomy often taken as true by modern philosophers. Several decades ago, Karl Popper advanced an hypothesis that equated falsifiability with testability. However, an oft-overlooked facet of testability is the logical duality of propositions and proofs. Logical duality says that if there is falsifiability, there must also be a concept of verifiability. Almost no one talks about verifiability independent of falsifiability in philosophical problems, despite its crucial importance to the hard sciences and engineering.

We can prove the non-equivalence of falsifiability and testability with a simple truth table. The columns denote true and untrue claims, respectively, and the rows correspond to whether a claim is verifiable or falsifiable. This means there are four elemental types of claims, as follows:

There are only two types of grey area: Unverifiable truths, and unfalsifiable falsehoods. Importantly there are two quadrants of the chart that correspond to testable and provable claims--not only a one-dimensional category, the "falsifiable", as Popper's fallacy is commonly misrepresented to imply.

As a consequence, falsifiability only matters for claims that are false. If they are not false, there does not need to exist a mechanism for proving them false--that would be immaterial, just as there does not need to exist a mechanism for proving a false claim to be true.

Christianity does not need to be falsifiable because it is not false.

It is however verifiable as all truly converted Christians can attest. Lennox's proof is completely valid. He is echoing immaculately scientific Scriptural invitations:

If any of you lack wisdom, let him ask of God, that giveth to all men liberally, and upbraideth not; and it shall be given him. But let him ask in faith, nothing wavering. For he that wavereth is like a wave of the sea driven with the wind and tossed. For let not that man think that he shall receive any thing of the Lord.

James 1:5

I would exhort you that when ye shall read these things, if it be wisdom in God that ye should read them, that ye would remember how merciful the Lord hath been unto the children of men, from the creation of Adam even down until the time that ye shall receive these things, and ponder it in your hearts. And when ye shall receive these things, I would exhort you that ye would ask God, the Eternal Father, in the name of Christ, if these things are not true; and if ye shall ask with a sincere heart, with real intent, having faith in Christ, he will manifest the truth of it unto you, by the power of the Holy Ghost. And by the power of the Holy Ghost ye may know the truth of all things.

Moroni 10:3-5

We don't need to be confused. Outsourcing this experience regarding the one thing that matters most--who we will become and the conditions we will enjoy or not enjoy for eternity--would be most unwise.

Failure to falsify must not be conflated with untestability.

Importantly, real scientific inquiry requires patience, diligence, and even faith--because it might not be immediately apparent at first whether an inability to falsify a claim is because it is true, or we just haven't found a means of demonstrating its falsity yet, or vice-versa. If we insist on the falsifiability of a claim as a prerequisite to considering it testable, we are betting on its falsity thereby. On the other hand, if we hold out for the verification of a true claim, eventually we will be rewarded for our persistence, because the thing is true! The only bottomlessly fruitless proofs are endeavors to prove false claims true or true claims false. Those who do not endure in the correct avenues are simply giving up on truth before they find out. This is one reason why faith is so essential! You can stop working a problem at any time based on your presuppositions. But presuppositions are not sure knowledge of truth. Discovery is and always has been a matter that requires patience, deep thought and commitment.

Consider one of the most basic building blocks of scientific and philosophical proofs: Modus ponens. The rule of Modus Ponens states that if you have a true proposition, P → Q (P implies Q), and you also have that P is true, then it follows that Q must be true. Importantly it is not possible to disprove the proposition that P → Q without satisfying the condition P. In Scriptural terms, God requires that we meet His conditions to receive a testimony that Christianity is true. Those who do not satisfy the condition P can have nothing to say about P → Q; they have no experience in the matter because they have not actually tested it. Testing is as much about effort as it is about the theories of falsifiability and verifiability. Discarding a possibly true claim as untestable merely because it is not falsifiable is simply laziness and apathy making the subjective decision for you that it is not worth the effort to find out. Such never arrive at the treasures of true discovery, and the personal verification of timeless truths.

Thousands of claims thought impossible by philosophers and mathematicians have been proven true over the years through patience, perseverance and diligence. The fact that a result has not been obtained yet does not mean that it never will be. In other words, faith is the crucial component of the scientific method, and the fruit of faith is knowledge of truth, and love of virtue. What the mainstream says doesn't matter. Truth is not relative in the slightest, but all proof is personal--and you must be the experimenter. Welcome to the journey of conversion, which happens to include the real scientific method, without misdirection or artificial limitations.